s:?: :?: s:?:
I have searched and can't find anything here - sorry if I've missed it.
I have standard size wheels and tyres, Yokahamas.
They've only lasted 19k miles.
Everyone is telling me different pressures to put in - now I have no idea - book says 32psi rear, and 26 front, but everyone else says this is wrong.
Have you a definative answer?
Thanks if you have
That sounds right for the stock pressures on a prefacelift car.
Mine lasted a lot less than that s:twisted: :twisted: s:twisted:
Quote from: "flying":?:
I have searched and can't find anything here - sorry if I've missed it.
I have standard size wheels and tyres, Yokahamas.
They've only lasted 19k miles.
Everyone is telling me different pressures to put in - now I have no idea - book says 32psi rear, and 26 front, but everyone else says this is wrong.
Have you a definative answer?
Thanks if you have
What you have quoted above from the book is the correct pressures to use, and the ones I have been for nearly three years s:wink: :wink: s:wink:
Quote from: "flying"I have standard size wheels and tyres, Yokahamas.
They've only lasted 19k miles.
some people on here have trashed theres in under 10K!
Quote from: "flying"Everyone is telling me different pressures to put in - now I have no idea - book says 32psi rear, and 26 front, but everyone else says this is wrong.
who is everyone???? and what do they know? are they informed enough to decied?
Quote from: "kanujunkie"Quote from: "flying"I have standard size wheels and tyres, Yokahamas.
They've only lasted 19k miles.
some people on here have trashed theres in under 10K!
My Proxes T1R's on the rear lasted a mere 6 months(ish) now I do roughly 12000 a year so thats 6000 Miles s:twisted: :twisted: s:twisted: I enjoyed them anyway, trying to be more gentle with this set, but once it starts sliding, just cant stop myself... s:roll: :roll: s:roll: s:lol: :lol: s:lol:
I use 25 Front, 32 rear on stock RE040.
Found the 1 psi made just the difference
Quote from: "flying"book says 32psi rear, and 26 front, but everyone else says this is wrong
I'm not trying to be funny, but why do people think the chassis engineers at Toyota might have got this wrong?
Quote from: "red_leicester"I'm not trying to be funny, but why do people think the chassis engineers at Toyota might have got this wrong?
I thought he was unsure of the toyota stated pressures, not saying that they had got them wrong.
On the other hand the default pressures are set to be nice and safe and understeery. I found that a slight adjustment (with the stock yokos) improved the handling quite a lot and had be grinning far too much... s:twisted: :twisted: s:twisted:
Mine understeered at first on the stock tyres. Dropped the fronts by 2psi and it cured the understeer.
As far as tyre wear is concerned, if they are wearing evenly across the width of the tyre then the pressures are OK. If the pressure is a long way off then the wear pattern will be uneven, too high and the centre will wear, too low and inner/outer edges will wear.
Tool fast into roundabouts and the outer edges will wear.
Quote from: "Moleshome"Mine understeered at first on the stock tyres. Dropped the fronts by 2psi and it cured the understeer.
As far as tyre wear is concerned, if they are wearing evenly across the width of the tyre then the pressures are OK. If the pressure is a long way off then the wear pattern will be uneven, too high and the centre will wear, too low and inner/outer edges will wear.
Tool fast into roundabouts and the outer edges will wear.
Thats interesting to know - my car seems to have 'no' front end with very little feel. Hoping dropping the pressures at the front may alleviate this. I had set them to 1.8 front / 2.2 rear (sorry, I work in BAR) as per the manual. Of course it is hard to say in this weather, but I hoped for a more positive turn-in.
ONly had the car a fortnight, currently running OE Bridgestone Potenza. The fact it has done 25k and ORIGINAL fronts still have 4mm was a good indication of how it had been driven! Rears were replaced under warranty apparently because of cracking - so are also new POtenza.
Quote from: "Moleshome"Mine understeered at first on the stock tyres.
In my experience this is usually a result of entering a corner too quickly.
Quote from: "red_leicester"I'm not trying to be funny, but why do people think the chassis engineers at Toyota might have got this wrong?
I absolutely agree with you. Toyota must have done a lot of research on a very big budget to determine what was the 'best' set up for the car. I don't have either the time or money to match this, so I'm happy to keep going on their set up.
... thinks ...
and if an insurance company investigates after an accident and finds that the tyre pressures aren't as stated in the manufacturers handbook, what happens next?
Just my 0.02.
Quote from: "filcee"Quote from: "Moleshome"Mine understeered at first on the stock tyres.
In my experience this is usually a result of entering a corner too quickly.
Well...yes, of course. The car won't understeer if it isn't moving fast enough. s;) ;) s;)
Quote from: "filcee"Quote from: "red_leicester"I'm not trying to be funny, but why do people think the chassis engineers at Toyota might have got this wrong?
Toyota must have done a lot of research on a very big budget to determine what was the 'best' set up for the car.
Surely Toyota did plenty of this and that to make it the way they want it. But guess if they are more interested in keeping the 99% of average joe owners on the road with extra understeer or making the car faster for the 1% of capable drivers..?
No manufacturer can make a car that's perfect for everyone. That's why we mod them. Some want more power, some want different handling, some just get a bodykit and huge wheels. Everyone should think of what they want and like, not what someone else or Toyota did. s8) 8) s8)
That said, yes, the stock setup is very, very good for most. Probably next to perfect for plenty of people.
Quote from: "Chris_h"Thats interesting to know - my car seems to have 'no' front end with very little feel.
to:
Quote from: "Chris_h"ONly had the car a fortnight, currently running OE Bridgestone Potenza. The fact it has done 25k and ORIGINAL fronts still have 4mm was a good indication of how it had been driven!
That's why you've got no turn-in, IMHO.. The rubber on original fronts with that kind of mileage & age will have long since gone off (the OE Bridgestones do that
very quickly) - I was in much the same position when I got mine and the handling was awful at anything over 'pootling' speeds.
Change 'em (to a nice set of Toyo T1-Rs)
Quote from: "filcee"I absolutely agree with you. Toyota must have done a lot of research on a very big budget to determine what was the 'best' set up for the car.
I doubt they did that at all.
They did a lot of research on a big budget as to what was the best
comporamise that would offer reasonable performance without pitching 90% of drivers off the road if they get it just a tiny bit wrong. That's nowhere near ideal for the fastest speeds, but it saves them having to recall a whole range for fear of a class action suit.
Quote from: "filcee"and if an insurance company investigates after an accident and finds that the tyre pressures aren't as stated in the manufacturers handbook, what happens next?
Insurance companies are pretty anal, yes - but after any accident hard enough to require that kind of investigation (so we're looking at write-off or near write off) it's highly likely that the tyres will be detached from the car, or could be demonstrated to have suffered an impact hard enough to lose a significant amount of pressure & integrity through the accident alone.
Of course, there are tell-tales of
chronic under or over inflation (tread wear), but that's a very different thing to dropping a psi or two to accommodate for tyre differences and personal preferences when it comes to handling.
For a start - as soon as you are running on anything other than the OE tyres, you need to adjust the pressures just to maintain the handling attributes that Toyota designed into the car due to differences in sidewall stiffness, rubber compounds and even tyre weight.
Quote from: "filcee"... thinks ...
and if an insurance company investigates after an accident and finds that the tyre pressures aren't as stated in the manufacturers handbook, what happens next?
What would happen to every Joe Bloggs who has left his tyres alone after the nice garage/tyre place etc has wrongly inflated them?
I think they'd be far more at risk here than someone who deliberately keeps the pressures a couple of psi each side of the reccomended.
Quote from: "aaronjb"That's why you've got no turn-in, IMHO.. The rubber on original fronts with that kind of mileage & age will have long since gone off (the OE Bridgestones do that very quickly) - I was in much the same position when I got mine and the handling was awful at anything over 'pootling' speeds.
Change 'em (to a nice set of Toyo T1-Rs)
Quote from: "filcee"I absolutely agree with you. Toyota must have done a lot of research on a very big budget to determine what was the 'best' set up for the car.
I doubt they did that at all.
They did a lot of research on a big budget as to what was the best comporamise that would offer reasonable performance without pitching 90% of drivers off the road if they get it just a tiny bit wrong. That's nowhere near ideal for the fastest speeds, but it saves them having to recall a whole range for fear of a class action suit.
.
Thanks for that Aaron, was thinking that the age of the tyre would make a difference. I am thinking of changing just the front two, do you think a new set of POtenzas would yield a huge benefit in feel and grip? I am tempted to go for some sticky fronts and leave the backs untouched (they are new Potenzas). I know some people on my forum insist on having all 4 the same, but in my experience it is not usually a problem unless you take it to extreme - i.e slicks on the front, remoulds on the rear = very unbalanced grip.
BTW, re Toyota recomended tyre pressures, this is simply based on a general guide for most owners - and probably the most neutral / safe handling set up. Having worked in product development for a large OEM in Europe and the US, I can confirm this is the approach.
I'm going to tinker with them just like I have done in other cars, its amazing how the feel can change.
Quote from: "aaronjb"That's why you've got no turn-in, IMHO.. The rubber on original fronts with that kind of mileage & age will have long since gone off (the OE Bridgestones do that very quickly) - I was in much the same position when I got mine and the handling was awful at anything over 'pootling' speeds.
To dredge up almost the contents of another thread - before my fronts were changed (32k miles), handling was pants with stock pressures in both. After changing them, handling was much improved - even though the new fronts were wrongly inflated and both at different pressures. After setting them back to stock pressures, I felt like I was back in an old pair of slippers. Needless to say the driving experience is now much improved.
Quote from: "aaronjb"Quote from: "filcee"I absolutely agree with you. Toyota must have done a lot of research on a very big budget to determine what was the 'best' set up for the car.
I doubt they did that at all.
They did a lot of research on a big budget as to what was the best comporamise that would offer reasonable performance without pitching 90% of drivers off the road if they get it just a tiny bit wrong. That's nowhere near ideal for the fastest speeds, but it saves them having to recall a whole range for fear of a class action suit.
Note the 'best' not best s;-) ;-) s;-) Apologies for my being obtuse, but thanks for explaining to everyone why I put my best in single quotes.
Quote from: "aaronjb"Quote from: "filcee"and if an insurance company investigates after an accident and finds that the tyre pressures aren't as stated in the manufacturers handbook, what happens next?
Insurance companies are pretty anal, yes - but after any accident hard enough to require that kind of investigation (so we're looking at write-off or near write off) it's highly likely that the tyres will be detached from the car, or could be demonstrated to have suffered an impact hard enough to lose a significant amount of pressure & integrity through the accident alone.
Good point - hadn't quite thought that through had I? s:oops: :oops: s:oops:
Quote from: "filcee"Note the 'best' not best s;-) ;-) s;-) Apologies for my being obtuse, but thanks for explaining to everyone why I put my best in single quotes.
Damn you s;) ;) s;) s:lol: :lol: s:lol:
I totally didn't spot the quotes.. s:oops: :oops: s:oops: s:) :) s:)
Looks like it is new front boots..
May see if I can get a decent price through one of the trackday companies, that way I can destroy my current fronts in the morning and see what difference the new ones make in the afternoon (hopefully without obliterating them)
Filcee - did you stick to the OE Bridgestones to match your rears? AM thinkning of mixing with Toyo as they seem much cheaper. According to my local fitter, the OE RE040 have a special code which translates to a unique compound for the MR2 - hence pricey!
I just topped mine up and the screen wash.
Couldnt remember this post tho so i put 28 and 32 I think. s:oops: :oops: s:oops:
Quote from: "Chris_h"Filcee - did you stick to the OE Bridgestones to match your rears? AM thinkning of mixing with Toyo as they seem much cheaper. According to my local fitter, the OE RE040 have a special code which translates to a unique compound for the MR2 - hence pricey!
Toyos are cheap enough to replace the rears aswell!
Aye - to be honest I'd recommend replacing all four. If all four are the same age you're likely to end up with a hideous grip imbalance even if you go with OE Bridgestones on the front (which, incidentally, I wouldn't do - they cost more IIRC, and turn to rubbish after 8-10k).
It's your car, but I'd say it's lunacy to have old slippery tyres on the back of a car that already has a reputation for pitching people into ditches (just search around here to see how many people have come unstuck, so to speak).
Quote from: "Chris_h"Filcee - did you stick to the OE Bridgestones to match your rears?
Yes - but only becuase the replacement RE040s on the rear only had about 3k miles on them. Next time I will replace all 4 together (when the rears go) as driving round dodgy fronts was fun, until the missus started complaining s;-) ;-) s;-)
Quote from: "Chris_h"AM thinkning of mixing with Toyo as they seem much cheaper.
Don't mix tyres - there's many a sad tale on here resulting from using mixed tyres. Search is your friend if you are curious.
Quote from: "Chris_h"According to my local fitter, the OE RE040 have a special code which translates to a unique compound for the MR2 - hence pricey!
That's a new one on me! FWIW I paid £143 for two front RE040s at the beginning of Feb at my local tyre dealer. The rears cost me £190 at the end of Oct last year. Don't know how your quotes compare, though.
Thanks for the info guys
My quote is similar for RE040 fronts c. £80 each. I haven't shopped around yet, but it seems a far cry from the £50 I have heard mentioned for Toyos. A part of the code relates to the compound (Z something - will look again when it is dry) apparently/ I wouldn't normally listen to the chaps at the large tyre fitting chains, but this guy seemed particularly knowledgable.
Problem I have is the rears also have only 3000 miles on them and are virtually new (were replaced under warranty due to cracking - before I owned the car). Don't really want to replace all 4 just yet, am thinking of getting a 2nd set of front rims (cheap scruffy used ones) to put Toyos on and then I can see how it affects the balance.
Still haven't really given my OE fronts a fair crack. Weather has been appalling and they are progressive in the wet - just seem lacklustre (if predictable) when pressing on round some empty roundabouts on a dry but very cold day..
Quote from: "Chris_h"Problem I have is the rears also have only 3000 miles on them and are virtually new
This is what I have. So far, no shocks in the handling department caused by the different mileages between front and back. I don't think, based on my experiences, that this will be a problem for you.
Quote from: "Chris_h"am thinking of getting a 2nd set of front rims (cheap scruffy used ones) to put Toyos on and then I can see how it affects the balance.
I'll say it again -
DON'T mix tyres. There are lots of stories of prangs as a result of mixed tyres. Use the search and you will find. £160 for tyres now will be a lot cheaper than the hike in your insurance, or the cost of repairs. Despite all of the "hairdresser's car" comments, the '2 is a proper sports car and if you muck about with things like mixing tyres it will bite you. And when it bites, it bites like any mid-engined car - straight to the scene of the accident you go. It's really not worth the few quid you will save today by opting for a couple of chepaer tyres "to see you through". Bite the bullet and get the RE040s and have peace of mind.
I'd buy a set of toyos all round and flog your rears on ebay or something.
Quote from: "Chris_h"My quote is similar for RE040 fronts c. £80 each. I haven't shopped around yet, but it seems a far cry from the £50 I have heard mentioned for Toyos.
My recent front Toyo TR1's were £35 each from mytyres.co.uk
At Christmas, I bought new Goodyear F1's. Must confess, as it has been handling so well, I haven't checked the tyre pressures. s:oops: :oops: s:oops:
OK, this morning I checked and the fronts were both 28, but one rear was 36 and the other 22 !!!
(The rears are the type with the firmer side walls - maybe that is why I hadn't noticed.)
Anyway, as I couldn't remember the correct pressure I've put both rears to 28. Now I want to play with the pressures, but have no experience as to what I am looking for. What changes in handling should I expect if the tyres are over or under inflated - other than the obvious!
Thanks for any help advice you can offer.
Cheers
Nathan
I must admit I am not sure of what pressures I should be using so it's a case of trial and error for me. As I mentioned on a different thread, so far the best configuration is 28 front/32 rear.
Tyres are pre-facelift stock size Toyo T1-Rs. On post face-lift I would probably start at 28 front/34 rear...
I work in BAR - 1.8 to front and 2.2 to rear as per the manual.
Most cars recommend having a slightly higher rear pressure, but with the engine being rearwards, this is why you need much more in the back.
Anyway, I have now dropped the fronts to 1.65 BAR and there seems to be more front end bite and turn-in grip. The nose definitely feels more positive. I changed them 3 times today as I hooned around the country lanes and am settling on this setup for the time being - until I replace all 4 tyres at least. It has finally given me some confidence in the car which was sorely missing in the first few weeks of ownership.
With a previous car (Ford Racing Puma) small changes to the front made huge differences. Lower pressures almost always created more perceived front end grip, but reduced feedback. Raising the fronts made it quite entertaining to drive as it made the fronts more 'skittish'. However, the FRP had a ridiculous amount of front end grip to start with, so losing some front end wasn't a problem.
Funny you should mention tyre pressures!! I noticed that my left rear looked a bit down when waxing the car today (must be mad - it was pretty cold!) Anyway, looked up the pressures in the manual - rears 32 & fronts 26. Had to put 20lb in the soft one - no wonder it felt a bit wooly. The 2 rears will need replacing soon. They are as on vehicle from new June 04 & done 18K YOKOHAMA ADVAN's. Car driven reasonably steady. Any suggestions for how much to replace, or alternative make. Been in touch with Silverstone performance re Turbo & Chrome Style Bar. Must admit prices far better than Toyota Dealer but will give turbo a miss at £4k - wife said I could use the money to buy her a new car, will twist her arm for the style bar though!
Black 04 MR2 - Only extras TTE Sports spoiler, TTE exhaust & Front Spats - looking at the style bar & would love the turbo! Not as rich as some of you!
So can I summise that for the post 03 (15" front 16" back) the pressures are 26 and 32 PSI respectively?
How about for pre-facelift models?
Follwing on from this thread, I thought I'de check the tyre pressures on my 2 (picked up almost a week ago).
It was 32 front and 26 rear for a preface lift model.
I think someone read the manual wrong s:roll: :roll: s:roll: . Having reversed that the handling is sooo much better. It also feels a lot more planted on the motorway, it felt a bit skittish before hand.
Likewise, we had a new pair of Toyos put on last week and my wife was complaining that the car felt really skittish.
Turns out they put 32 in them (front) s:shock: :shock: s:shock:
Having had a search I can't really find the information I'm looking for.
A few weeks ago I had TTE springs fitted with the standard tyres on the front and dunlops on the rear and it felt like a go kart, I loved it. Following peoples opinions on tyres on this site I had it booked in for 4 new toyo t1-r's. I had them fitted and the nursed the car for 500 miles.
I can't seem to get on with the new tyres. The front end seems a bit vague and the car feels skittish again on the motorway.
It feels like the old tyres did when they were set at incorrect pressures. I currently have the pressures set to 26 front and 36 rear. Because most people on here rave about them I'm surprised by my findings. So I'm blaming me before I blame the tyres. Any ideas what I'm doing wrong? any suggestions for alternative pressures?
Thanks, Ian.
i have them at 30 front, and 34 rear,
i must admit, i was really disappointed when i swapped to toyos, when ifurst drove away i thought, what have idne these are aweful.
but once igot the tyre pressure right and the tread nice and clean they are now great.
it is difficult to fault them in the dry and the wet, there is defo improvement. must admit the 040's are good, but ididn't like the tramlining.
rt, what pressures did you have them at to start with ? 26/32 ?
original was 28 front and 32 rear
I am using the 040s with stock pressures in. I find it is easy enough to have understeer or oversteer on demand, so stock pressures for road use would be OK with me.
Lots of talk about handling and mixing tyres. The critical time to discover what the car handles like on mixed tyres is just as one end gives up its grip. In this context, what is being discussed with handling is really about on limit handling, when the tyres are on that lovely border between stick and drift. This is a narrow band of behaviour for a tyre and as such, it would seem like a bad idea to have different tyres f/r on any car, let alone a mid engined one.
Also, different tyres work at different slip angles (to generate cornering grip). If the fronts and rears are too different, it can lead to a car where the handling balance never feels malleable, it generally gets difficult to load the rear with any conviction as the differing slip angles and resulting differing scrub will not permit the car to balance on the throttle.
I thought that the factory pressures were worked out based on load vs width vs section to provide a even contact patch and eventyre wear. You may get a bit more turn in with the fronts down a couple of pounds, but you may also get less ultimate grip and increasd shoulder wear. I never ran mine that low for long enough to notice shoulder wear, but did not like the loss of feel or ultimate understeer past the grip limit that dropping the fronts gave me.
Chris
i up'd mine by 2 psi front and rear because the side wall on the t1-r is softer than the 040's.
i find i have no problems with excessive understeer, and i can tell when the pressures aren't right as the car feels a little skitty when pushed and not a s planted.
Thanks RT, just what I wanted to hear! I guess I'll stop off this evening and re-arrange the pressures to 30/34 and see how I get on.
I was following an A3 this morning and he was carrying far more speed through corners than I could even dream of at the moment, so not good! s:evil: :evil: s:evil:
Thanks all!
Quote from: "rtbiscuit"i up'd mine by 2 psi front and rear because the side wall on the t1-r is softer than the 040's.
i find i have no problems with excessive understeer, and i can tell when the pressures aren't right as the car feels a little skitty when pushed and not a s planted.
if your T1-R's have RF written on them then they have re-inforced sidewalls, but 2 psi is going to make no differenc to sidewall strength when compared to the cars weight acting on it laterally. However it will be enough to curl the base of the tyre causeing a reduced footprint, hence the skittishness
I found I needed at least 4 psi extra
Are these RF'd T1-R's a new thing then Stu?
Quote from: "simonp"Are these RF'd T1-R's a new thing then Stu?
pass, i read it on Camskills website earlier, but do you think i can find it now s:roll: :roll: s:roll:
Quote from: "simonp"Are these RF'd T1-R's a new thing then Stu?
I've got RF'd rears and standard fronts. Markiii sugestion of upping the pressures to 30/36 has improve things slightly (thanks for the advice s:) :) s:) ) but still not a patch (handling wise) on RE040s IMO.
I'm getting more grip the the wet tho - Overall I think I'd prefer better handling in the dry and drive like a granny in the wet.
Not sure what mine are, I'll have a look later on. If I don't get much improvement soon, I think I'm gonna have a look for some alternatives.
Quote from: "simonp"Are these RF'd T1-R's a new thing then Stu?
Quite a few on Toyos website (http://www.toyo.co.uk/productdetail.php?identity=products&product_id=2)
T1-Rs on mine are run at 28,35. You need the extra 3 psi on both tyres to reduce the tyre wall flex and then drop the front by 1 psi to help reduce the rear grip imbalance.
Any higher and I can't start the serious grip drop off.
RE040s were run at 25/32 as per recommendations with 1 psi off the fronts.
After extensive testing I've finally settled on about 28-30 on the front and 36 on the rear but I still don't like the tyres.
Apologies in advance for my ropey explanation of my thoughts, but here goes .......
They feel too unpredictable. When going around fast sweeping corners any change of speed forces an excessive change in turn angle. When going around tighter corners it feels like they need to move the weight of the car on the tyres first and then they turn in. I could handle the symptoms, but not in the excessive way that the toyo's perform. So as soon as I can afford to replace them I will be.
For what it's worth, I've also checked the tyres and they do have reinforced stamped on the side, so I guess they are the new ones that people have spoken about.
This is just my opinion of the tyres (Toyo T1-r's), I know a lot of people get on with these tyres, but unfortunately I wasn't one of them.
Yep, that's a fair review of the performance and an exact summary of the sympoms that I've have- I feel quite uneasey when cornering at anything other than medium speeds. I'm running 30/36 to get some of the stiffness back, unfortunately understeer suffers & I loose allround grip as a result.
Did you go from RE040s to T1-Rs?
I think the car had bridgestones on the front and yokohama's on the rear (or something like that)
Yesterday, I eventually checked my tyre pressures for the first time ever (I have RE040s on a post facelift).
They were all @ 32psi! Seems Mr T are to thank for this, since it has been a few months since I got my last set of replacement alloys.
Wouldn't you think that a Toyota garage would at least be able to put in the correct tyre pressures ? makes you wonder how well they do other things such as servicing etc.
I assume they did similar when I got my previous set off replacement alloys a year earlier? I've always thought it was a bit wobbly when taking bends at anywhere above 70 mph! Seems I have probably never had the correct pressures throughout my ownership!
I've never had Mr T put the correct pressures in. I had 4 replacement wheels recently and they put different pressures in each tyre - ranging from 1 psi out to 4 psi!
When I was using mine regularly, I would check the tyres every weekend.
Hmmm
Tyre pressures for beginners:
Tyre pressures should be checked at least once a week and before a long journey. Tyres should also be inspected for cuts, bulges, nails other damage at time of pressure check. A brief visual check every time you get into the car can show if a flat is imminent.
Check the tyre pressures when the tyres are cold. Remember every 10 deg C will add around 1 psi to the measured pressure. A tyre sitting in the sun may have 20+ degrees C more temp than one measured in the evening. A tyre that has been run may be 40 deg C hotter than normal temp.
Don't forget to check your spare as well. It is easy to look like a tw@t when getting a flat spare out.
My experience with Toyos on another car tells me they are quite porous and need checking very regularly.
And for those with a little more knowledge:
The manufacturers generally use a tyre pressure that will give a optimally shaped contact patch. This is a product of tyre diameter, width, profile and load applied.
Dropping the pressure from the recommended setting will generally make the contact patch longer, thus the tyre, if on the front, will give a higher initial turn in rate as there is a greater contact patch length. This can also change the centre of the contact patch relative to the steering axis, so may also mimic a change in castor. Finally, the patch will potentially be wider at its ends, so the steering will generally have forces acting upon it averaged out over a more square patch. This in turn leads to less steering feedback but heavier steering. Finally, the tyre can roll more on its rim and will have uneven force across the tread width, resulting in rolling of the tyre carcass under load, uneven wear (tread edges) and of course, reduced overall grip. Transition between grip and slip may well be softened a little, making driving near the limit of adhesion easier. Alternatively, the deformation of the tyre may get to a point where snap loss of grip occurs.
Increasing the pressures will have the opposite effect to reducing them. The contact patch will become shorter, this will make the steering feel more direct as the feedback can be improved. The higher pressure will also lead to lower rolling resistance, potentially an effect similar to reducing castor (as drag is reduced and the patch gets wider relative to its length). The contact patch will be reduced in size, so outright grip may suffer. Transition between grip and slip can become very sharp as the lack of conformity in the tyre will potentially prevent deformation to accommodate roll induced geometry changes from the car. Pressure will be applied unevenly to the tread leading to increased pressure down the middle of the contact patch (increased force per unit area also) leading to worn middle section of tread.
In both cases, the wet running of the tyre may be adversely affected if the contact patch bias is mismatched. So running T1-R under inflated may cause the middle section of the tyre, the bit that does most drainage, to be pushed clear of the road surface by standing water, leaving the edges with their small void area to work toward drainage. A bad thing. Similarly, over inflating a Yokohama A043 with its wide centre rib may be bad as the drainage bits either side of centre and on the shoulders are relatively under loaded.
So adjusting the pressures from stock by small amounts will allow an individual to fine tune handling to taste, but done to excess will cause potentially unacceptable handling and wear trade off. For my money, I would not go past +/- 2 psi as consistently running at 2 psi out is known to cause visibly uneven wear. Others may find the trade off acceptable.
My front 040s are due for replacement. The 81V rated stock 185/55 R15 is currently not available, so may be thinking of something a little different.
A last thought for those new to the MR2 experience. The car responds well to a gentle approach to steering. Feed the front end in by increasing steering angle gently and it turns in fine. Hoik it in and you can get understeer. So before changing pressures, try not over driving the front end.
Chris
Quote from: "mrsmr2"I've never had Mr T put the correct pressures in. I had 4 replacement wheels recently and they put different pressures in each tyre - ranging from 1 psi out to 4 psi!
Don't worry all dealerships seem to be consistant with this s:? :? s:?