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Matt
Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22242
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Yes I do have another question as a matter of fact. The

Resolved Question:

Yes I do have another question as a matter of fact.
The car was purchased used recently. I don't particularly like tyres I don't know the history of so they are going to be replaced. The present set are a bit of a mixture of Dunlops and another budget make.
I am though slightly confused. The tyres fitted at present are 17inch 215/45V91 the user manual calls for 215/50, doesn't the difference affect the rolling diameter and therefore the speedometer readings?
However, 215/45 (Goodyear) are considerably cheaper than 215/50 and easier to obtain, the 215/50 being a special order in some outlets.
So my question is, is it Ok to continue to use the presently fitted 215/45 or should I return to the specified 215/50? I should add from a driving point of view I am not having any particular problems with the current tyres except I don't entirely trust them as I don't know their history of any possible previous damage.
Regards
Peter Lewin
Submitted: 3 years ago.
Category: Car
Expert:  Matt replied 3 years ago.
Hello

the difference between the 2 tyre sizes doesn't amount to a huge amount ( about 3.3% speedo error) so its quite possible the original owner went this route to save some cash

obviously with the slightly smaller tyre your gearing will be slightly lower so the car will accelerate better but suffer from reduced fuel consumption on a run

I'd say providing the tyre walls aren't bulging or cracked and there's no excess vibration and they grip OK in the wet then run them on until they are worn enough to replace
Customer: replied 3 years ago.

Thank you Matt,

Further investigation from three local tyre dealers/fitters finds that in their records and back listings 215/45 are indeed the correct tyre. It seems the only reference to the 215/50 tyre is in the Toyota handbook. One tyre dealer actually said the the problem with handbooks is that they are generic. One would have thought the manufacturer would know what tyres they specified. My nearest Toyota main dealer is surprisingly vague on the subject.

The same car (different model) is available with a 16inch wheel. Although I haven't looked into it at all, I wonder if this is where the confusion might lie.

In any event, I have ordered 4 new 215/45 Goodyear Eagles (for the lowest noise rating) they are to be fitted tomorrow (04/12)

As far as the 3.3% speedo error is concerned, would that be faster road-speed or slower than that indicated? just curious as in practice I wouldn't think in general use it would make much difference unless I was using the cruise control at the legal limit.

Regards

Peter Lewin

Expert:  Matt replied 3 years ago.
Hello Peter

if the tyre is bigger than it should be ie. the 215/50 the 3.3% error will have the speedo underreading so you would actually be travelling faster than indicated

and the Goodyear eagle is an excellent tyre you should be very happy with it
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