Advice on Wheel/Tyre sizing

[gavw71]

Before I start, I realise from my searches that this topic has been "done to death" but I just want to reassure myself I'm going the right way.
Ok, I'm fed up with the state of the alloys on my car and recently hatched a plan to buy some face lift wheels off ebay and have them re-furbished, but I was outbid.  
So now I'm looking at going down the new wheel route, but after a few hours of searching on here at the weekend, my head is now spinning.  
I think for cost and potential rubbing issues, I'm going to go for 16" all round and I found this post:

by Ilogik on Mon Mar 16, 2009 9:24 pm
Look for a good set of light weight wheels, 16x8 et 35 on the rear with a 225/40/16 fits nicely. Fronts i am personally running 16x7 et 40 i think with 205/45/16, these sizes and offsets fill the arches perfects, rears sit flush.

So I thought I'd go with the above set-up.

Then, out of curiosity, I crunched the numbers in this offset calculator.
 http://www.1010tires.com/WheelOffsetCalculator.asp
The results suggest there would be less inner clearance and the wheels would extend out more.
 
To further complicate matters, I used the following tyre size calculator in an attempt to keep the outer diameters as close to standard as possible, but this has just added to my confusion.
 http://www.1010tires.com/TireSizeCalculator.asp

OEM front 6"x15", ET 45, with 185/55/15 tyres = 584mm overall diameter  (currently fitted)
OEM rear 6.5"x15", ET 45, with 205/50/15 tyres = 585mm overall diameter  (currently fitted)
OEM rear 7"x16", ET 45, with 215/45/16 tyres = 599mm overall diameter

205/45/16 tyre = 590mm overall diameter (suggested tyre size)
225/40/16 tyre = 586mm overall diameter (suggested tyre size)

I realise the difference is only 6mm, but could this coupled with the change in offset cause a problem with regards to rubbing?

I appologise if it appears I'm questioning what other people are saying - that's not my intention - as I said earlier, I just want to know if I'm going the right way.

[Wabbitkilla]

I wouldn't take ilogik's advice as gospel as he's relatively inexperienced with the MKiii MR2.

You need to go for as close as possible to the standard ET.
Someone with more experience of choosing wheels will come along soon as i just refurbished my own.

[GSB]

I like this guy already, he's done his homework...

WK is quite right, the MR2 has an unusual offset, and is ridiculously sensitive to changes in tyres, wheels, offsets, pressures and anything wheel related. Its best to stick as close to stock settings as possible, unless you need to fill the arches on wide bodykit, in which case you'll need an offset miles away from standard,

Back to your car though. First, do you actually need an 8" wide rim? Thats a lot of extra unsprung weight. If theres no benefit in having it, and I would suggest that in 99.9% of cases their isnt, then stick to a lighter, narrower rim.

As for tyres, theres usually a good reason that the "right" size isn't fitted, and its usually a question of availability. Tyre specs on the calculators are great, but the tyre makers rarely make tyres in every size, so if we want to deviate we have to get a "best fit" from whats available on the market. If done with care, the differences in radius can be minimised.

[gavw71]

First, do you actually need an 8" wide rim?

I thought about an 8" rear with a 7" front as this seemed in keeping with the set up on face-lift models, ie 16"x7" & 15"x6". However, after looking at various suppliers, it  would appear that 15"x6.5" and 16"x7" are more commonly available sizes. Also, the 0.5" difference in width is obviously the same as that on pre face-lift models, ie 15"x6" & 15"x6.5".

As for tyres, theres usually a good reason that the "right" size isn't fitted, and its usually a question of availability.

As in Toyo don't make a T1-R in 215/45/16 - which I think is the correct size for an OEM 16"x7" rear!  s:roll: :roll: s:roll:

So, now it looks as though I've narrowed my wheel search down to 15"x6.5" front & 16"x7" rear, with TSW Catalunyas and Team Dynamics Monza R's or Pro Race 1.2's all in the frame (should be speaking to someone at Demon Tweeks tomorrow for more advice/head scrambling!)

Now for the tyres!

Fronts should be easy, I can stick with 185/55/15's or move up to 205/50/15's - although this tyre size calculator says 185/55/15's are ok on 5"-6.5" rims, so the 205's may be the better option.

To keep a 10-20mm stagger (and hopefully avoid those ditches!) I should be looking at 205/45/16's (with 185's) or 225/40/16's (with 205's) but this is where this tyre size calculator sticks it's oar in again and tells me 225/40/16's  need 7.5"-9" wide rims. I've seen this size recommended by Markiii in another thread, so I know it must run ok and the overall diameter is as near as dammit the OEM 205/50/15 rear. Or I could wait for Toyo to do a T1-R in 215/45/16!

Please help!  s:flame: :flame: s:flame:

[markiii]

out of those wheels I'd go with teh pro race as they are the lightest

tyre wise

I'd go 195/50/15 and 225/40/16

[gavw71]

out of those wheels I'd go with the pro race as they are the lightest

tyre wise

I'd go 195/50/15 and 225/40/16

Thanks for the info Markiii. I've had a look on another tyre/wheel comparison site which shows a 225/40/16 will be ok on a 6.5"-8.5" rim. I'm happy with that, because the overall diameter of the 225/40/16 compared to the OEM 205/50/15 is almost identical.

With regards to the 195/50/15 though, the overall diameter is 8mm less than the OEM 185/55/15 - is this intended to reduce the sidewall height (for steering/handling purposes) or is it to prevent the possibility of rubbing in the wheel arch due to the wider tyre and rim?

Finally, I like all the wheels and would probably go for the Pro Race on weight grounds now, but 'er indoors has expressed a preference for the Monzas, so unless I can hoodwink her, Monzas it is!

[markiii]

it's to keep the stagger correct front to back

[gavw71]

Thanks for that Markiii   s:wink: :wink: s:wink:

[nickyb]

it's to keep the stagger correct front to back

Hi Mark - have narrowed wheels down to Team Dynamics Monza Rs or Jets (both = ET45), or TSW Modenas (ET40).

Re my pre-facelift 2, 15 inch, et45, and the front = 6 inch and the rear 6.5....

2 urgent hopefully final queries pls (need to order them Friday so can pay off before my tax year end 31 March)!

1.  Any thoughts re the above wheels and their effect on the car? Same or similar ET so hopefully won't rub?  Think they're all heavier than standard wheels, so will the weight affect the handling?  Anything else?!  Tried calling TSW for the weight and, despite lots of asking (!), all they could give was the BOXED weight...10.4kg/22lbs! Still waiting to hear from TD.

2.  Think all 3 don't come in 6 or 7 inch so would 6.5 all round be OK?  Is this the stagger you mention, or will the wheels sort it?

3.  On which point, I don't want to go the Toyo route as I love the positive turn-in of the Bstones - so would the standard size 185/55/15 and 205/50/15 REO40s be OK?

Thanks - sorry to be  pain!   s:| :| s:|

[markiii]

if your keeping stock widths then stock tyres will be fine

I'd stick witth the 45 offset personally

if teh wheels are heavier then yes it will effect handling, accelleration will be slower and turn in harder work, will either be sufficient that youw ill notice in eth real world, spends on how much heavier

I certainly noticed a massive difference when going for lighter wheels

[nickyb]

if your keeping stock widths then stock tyres will be fine

I'd stick witth the 45 offset personally

if the wheels are heavier then yes it will effect handling, accelleration will be slower and turn in harder work, will either be sufficient that youw ill notice in eth real world, spends on how much heavier

I certainly noticed a massive difference when going for lighter wheels

How much lighter are yours? Your info said standard are 14.6/15.2 lbs...

Oh, god - now I'm thinking I should go for Wolfrace ProLites - but I don't like 'em as much visually...any other 'spoke-y' suggestions welcome!

Re keeping to stock widths, as mentioned all of the wheels seem to come ONLY in 6.5 x 15, so will that be OK all round (instead of 6 front/6.5 rear)? - and with standard 185 front/205 rear tyres?

[markiii]

205s will be fine 185, probably but thats about there limit

lighterweight wheel for me were when moving back from heavy 17" to stock wheels

[gavw71]

Just a quick update, looks like I'll be going with the Monza R's. That way, I can get a half inch stagger, with 6.5x15" front & 7x16" rear. Plus it keeps 'er indoors happy!  s:D s:D  
To get a stagger with the Pro-Race 1.2's means going 7x17" front and 8x17" rear (as they don't do this rim in 6.5x15) with 205/40/17 & 225/35/17 tyres respectively. The fly in the ointment here is you can't get T1-R's in 225/35/17, so I'd have to go with another brand tyre, when I'm really looking forward to having Toyo's on.
So Monza R's it is.

[Ilogik]

if you want some slightly wider wheels that fill the arches check out styledynamix.co.uk, otherwise look up compomotives  and also coord sport
 m http://www.part-box.com/index.php?cPath=81_715 m
 m http://www.imagewheels.co.uk/ m

As for aesthetics and handling id say a wider wheel on the back with a good offset is good with proper geometry set up.   If you want your wheels to sit inside the arch for 45 offset.

Rear of mine.


here is a good list of wheels and combo tyres to with pictures so you can see how the car will sit.

 m http://spyderchat.com/forums/index.php? ... opic=29816 m

[markiii]

wish we'd thought of that

 l viewtopic.php?f=8&t=9911 l

  s:oops: :oops: s:oops:

[Ilogik]

wish we'd thought of that

 l viewtopic.php?f=8&t=9911 l

  s:oops: :oops: s:oops:

Indeed it does but 85% if them lack offset sizes.

[gavw71]

After a rush of blood this morning and hours of trawling the subject here and on SC, I've ordered the following from Demon Tweeks:

Team Dynamics Pro-Race 1.2 rims, 17x7" et 38 front, 17x7.5 et 45 rear.
Falken 452 tyres, 205/40/17 front, 225/35/17 rear.

I realise the Falkens don't get the same kind of write-ups the T1-R's are getting but hopefully, they'll be OK! Also, I don't expect any rubbing issues with the above sizes and offsets.

Just got to wait now for them coming!  s:bounce: :bounce: s:bounce:

[markiii]

I think your fronts may be a little close, but let us know how you get on
  s:D s:D

[nickyb]

After a rush of blood this morning and hours of trawling the subject here and on SC, I've ordered the following from Demon Tweeks

Must be something in the air...I finally took the plunge and ordered Wolfrace ProLites, shadow chrome, last week from alloywheels.com (at a big discount compared with other suppliers) - just received them, and out of the box they look fantastic.  
Had to go for 4 x 6.5 (x 15) as 6 not available - am assured by the supplier, and several other ones, that they'll be fine..... Will be WheelGuard-ing them over the weekend in a bid to keep 'em looking better than the originals! To be fitted, with standard Bridgestones (185 front/205 rear), next week.
Thx for all the help. Will feed back asap...happy Easter!    s:) s:)

[gavw71]

I think your fronts may be a little close, but let us know how you get on
  s:D s:D

If I've done my homework right, the new set up on the front should only be 3mm closer to the suspension etc than the original, touch wood!  s:scared: :scared: s:scared:  

The overall diameter for the new front should be 596mm, while the original is 584mm, so hopefully, the 6mm difference wont cause a problem.

In addition,

Rears 225/35/17 offset 45 (7.5 wheels) Yokohama SDrives on Team Dynamics 1.2 Pro Racers
Fronts 205/45/16 offset 38(7.0 /)

Lowered 30mm TTE.

I realise cj's running a 205/45/16 on the front, with an overall diameter of 590mm compared to 596mm for a 205/40/17, so I don't think the extra 3mm will hurt!  s:scared: :scared: s:scared:  
 With regards to the gap between tyre and suspension etc, this should be the same, as the rims and tyres are the same width. He doesn't mention any issues and he's also lowered 30mm - mine's standard - so with any luck, I'll be OK.
Obviously, I'll post how I end up, but that will take a couple of weeks depending on delivery.

[Ilogik]

just quick question if the pre facelift wheels  et 45 surly a 38 will stick out further away from the strut? so shouldn't touch at all, or am i getting lost somewhere. Think you should be fine mate, I have 16x7 et 42 and no catching.

[gavw71]

just quick question if the pre facelift wheels  et 45 surly a 38 will stick out further away from the strut? so shouldn't touch at all, or am i getting lost somewhere. Think you should be fine mate, I have 16x7 et 42 and no catching.

I think offset refers to the distance between the centre line and mounting face of a rim. So in the case of positive offsets, as the et decreases, so does the distance between the mounting face and the centre line, so the distance between the inner face of the rim and the suspension etc increases.

In my case though, the 7mm gained by dropping the et is swallowed up by the increase in rim and tyre width - 20mm difference between 205 and 185 means 10mm either side, so I should be 3mm closer to the suspension.

Just to finish, what width are you running on the front?

Many thanks, Gav

[Ilogik]

just quick question if the pre facelift wheels  et 45 surly a 38 will stick out further away from the strut? so shouldn't touch at all, or am i getting lost somewhere. Think you should be fine mate, I have 16x7 et 42 and no catching.

I think offset refers to the distance between the centre line and mounting face of a rim. So in the case of positive offsets, as the et decreases, so does the distance between the mounting face and the centre line, so the distance between the inner face of the rim and the suspension etc increases.

In my case though, the 7mm gained by dropping the et is swallowed up by the increase in rim and tyre width - 20mm difference between 205 and 185 means 10mm either side, so I should be 3mm closer to the suspension.

Just to finish, what width are you running on the front?

Many thanks, Gav

i thought a 38 would be low enough, if needed, you can pick up some 3mm spacers from halfords pretty cheap.