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[24_Valve]

I'm running on 205/65 tyres and just been offered a nice pair of 205/60's... I know that tyres must be matching pairs so thats not an issue.... question is: if I run 65's on the rear and 60's on the front would it cause any problems? not talking about MOT requirements etc.. just practical implications; i.e. ABS/TC (picking up different wheel speed?) or speedo reading being thrown out of kilter... and do I have wheel speed sensors all round or just the (rear) driving wheels. Are sensors sensors same for ABS/TC as for Speedo? thanks. theoretical question only, so, informed opinions only please... don't want an onslaught of criticism

[Mr Skrunts]

If it were me, I would keep the correct size on the rear this would give the correct speedo reading etc.

60 versus 65 profile, not a great deal in it.  On a tyre comparison chert I doubt that much difference.

Lower profile on the front, may dip the head light beam a tad, not sure if it will affect ABS.  Maybe wrong but dont think TC should be an issue as that cuts the the power as the rear wheels slip.

Could/would affect a claim in the case of an accident.

[24_Valve]

Thanks mate 

[24_Valve]

so long as they don't affect ABS/TC then i'll pick 'em up & just let the insurance Co. know, once fitted 

[feeutfo]

Can't see 5 mill difference in profile making much odds, but by no means sure tbh.  :-/

But being belt and braces I would ring the insurance company first in case they refuse to cover, unlikely though probably?

[2woody]

this WILL make a difference. you'll have a different rolling radius at each end of the car. The ABS will think you're much closer to locking up than you atually are, therefore will intervene sooner and lengthen your braking distances.

not to be recommended.

TC won't be affected, speedo also not affected if the undersized tyres are on the front.

[tidla]

how theoretically cheap are we talking..

[24_Valve]

Posted by: tapper888 Yesterday at 22:57
how theoretically cheap are we talking..

£10 each...

Posted by: 2woody Yesterday at 22:49 this WILL make a difference. you'll have a different rolling radius at each end of the car. The ABS will think you're much closer to locking up than you atually are...

"you'll have a different rolling radius at each end"

thanks 2woody i thought it might cause an ABS issue but didn't know for sure 

[Broomies Mate]

Can't see 5 mill difference in profile making much odds, but by no means sure tbh.  :-/

But being belt and braces I would ring the insurance company first in case they refuse to cover, unlikely though probably?

The profile is measured not in Millimeters, but as a percentage of the overall tyre width.   

As said, wont make much difference for speedometer reading.  I cant see it playing up with the ABS too much either.  :-/

[2woody]

actual accuracy depends on how accurate it is now - expect between 0% error and 8mph optimistic at 60mph.

205/60 is 843 wheel revs per mile
205/65 is the correct 817 wheel revs per mile

that equates to a speedo error of 3.1% on top of what you already have.

3% is outside what the ABS will be programmed for - so expect longer stopping distances.