Tyre Spec and Speedometre

Ghuraba

Ghuraba

Ghuraba

Associate
Joined
17 Oct 2002
Posts
1,332
Location
Leeds
Hi there.

I was wondering is there a legal requirement for tyres to be within a certain spec for a car. Meaning if the original tyres on a Ford Focus were 195/60/15 then when the speedometre says I am doing 70mph then for my car & tyres should mean I am doing 70mph. All other variables taken into consideration of course.

So if I fitted 195/50/15 then when the speedometre says 70mph based on a tyre calcualtion website I would actually be doing 65.6mph.

So legally and in terms of insurance would this be allowed? Or is there a limit as to how much you are allowed to out of the standard fit + or -?

Thanks

Michael
 
No idea to be honest but they don't test the accuracy of your speedo at an MOT do they? The only other problem you might have is with insurance as you'll be deviating away from the manufacturers spec.
 
Ghuraba said:
Hi there.

I was wondering is there a legal requirement for tyres to be within a certain spec for a car. Meaning if the original tyres on a Ford Focus were 195/60/15 then when the speedometre says I am doing 70mph then for my car & tyres should mean I am doing 70mph. All other variables taken into consideration of course.

So if I fitted 195/50/15 then when the speedometre says 70mph based on a tyre calcualtion website I would actually be doing 65.6mph.

So legally and in terms of insurance would this be allowed? Or is there a limit as to how much you are allowed to out of the standard fit + or -?

Thanks

Michael
Click to expand...

Legally its allowed as i believe there is a 10% tolerance for speedometer inaccuracies; as for insurance it depends on your company. Some insurers could claim that you have deviated from factory spec without informing them, so hypothetically they could refuse to payout if it came to a claim.

Personally i would just give them a ring so you are covered.
 
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