a bit unstable after tyre change... Normal?

[fstsven]

Had the rear tyres changed yesterday: Toyo proxes T1-R, stock dimensions.
Now I notice the car feels quite a bit unstable above 70mph, like there is a strong sidewind, only, there was no wind...   s:? :? s:?  
Anyone else experienced this; and will it get better if they are "scrubbed in"?  (I have only done 20 or 30 miles on them so far)
Oh yes, the fronts haven't been changed, since they were in good nick, and are Toyo T1-S.
Also, I have posted a question some time age about the steering wheel not being straight when driving a straight line; well, now it suddenly is   s:shock: :shock: s:shock:   Nothing has been done to the geometry or so, only the rear tyres changed...   s:?: :?: s:?:    Does anyone have an idea about how come?
Thanx in advance!
Greets

[Anonymous]

When I first picked up my 2 from new I had a steering wheel that was not quite straight and the car felt as you describe. I took it back and MrT kindly did a wheel alignment and it was cured.
IMHO you need a wheel alignment done.

[Anonymous]

You might get some instability due to the fact you're technically running on mixed tyres. It's also probably worth your while checking the pressures too, as the R's have a different sidewall to the S's.

[Anonymous]

what do you reccomend the tyre pressure to me at front and back?

[Anonymous]

What tyres are you running?