Are odd tyres on my back axle affecting my roadholding?
I have owned my approved used 70 plate Toyota Yaris Excel since just before Christmas. It doesn't hug the road as it should - tends to twitch to the left for no apparent reason on uneven surfaces (not due to lane deviation assist) and the requirement to hang on tight to the steering wheel leaves me with aching shoulders and hands. At 60.9 the mpg is nothing like the 70-72 I would expect in mild weather.
I have just realized that the new tyre on the rear drivers side wheel (17" alloys) doesn't quite match the other three. According to the handbook it should be a Bridgestone EP150 205/45/R17 84W but it's actually an 88W. I suspect that the mismatched tyres are causing the handling problems.
What do you think? The dealer swears they didn't change the tyre and in any case it shouldn't matter. It looks as though I'll have to buy a new tyre and I don't want to waste money.
I have just realized that the new tyre on the rear drivers side wheel (17" alloys) doesn't quite match the other three. According to the handbook it should be a Bridgestone EP150 205/45/R17 84W but it's actually an 88W. I suspect that the mismatched tyres are causing the handling problems.
What do you think? The dealer swears they didn't change the tyre and in any case it shouldn't matter. It looks as though I'll have to buy a new tyre and I don't want to waste money.
Asked on 17 March 2023 by Dorothy Dawson
Answered by
David Ross
We're sorry to hear you're having problems with your Yaris.
Having a set of matching tyres on your car is desirable, but not necessarily essential. The difference between your specified tyre and the one fitted is minimal - the 84 and 88 digits represent the load index, which in this case is a difference of 60kg. Unless the car is regularly loaded to capacity, this shouldn't be the cause of your issues assuming all the tyres are in good condition and have plenty of tread left on them. The recommended minimum is 3mm of tread, even though the legal minimum is 1.6mm.
A more likely explanation is that there is an issue with the wheel alignment, balancing or even suspension. We would suggest starting with getting all four tyres balanced and four wheel alignment at a reputable tyre service centre and then trying the car over a period of time to see if this solves the issue. If not, it would be worth getting the vehicle inspected to see if there are any worn or damage suspension bushes or components.
In terms of fuel consumption, if you are regularly achieving 60mpg or more then this is actually very good. The average Real MPG achieved by Honest John readers is around 54mpg.
Having a set of matching tyres on your car is desirable, but not necessarily essential. The difference between your specified tyre and the one fitted is minimal - the 84 and 88 digits represent the load index, which in this case is a difference of 60kg. Unless the car is regularly loaded to capacity, this shouldn't be the cause of your issues assuming all the tyres are in good condition and have plenty of tread left on them. The recommended minimum is 3mm of tread, even though the legal minimum is 1.6mm.
A more likely explanation is that there is an issue with the wheel alignment, balancing or even suspension. We would suggest starting with getting all four tyres balanced and four wheel alignment at a reputable tyre service centre and then trying the car over a period of time to see if this solves the issue. If not, it would be worth getting the vehicle inspected to see if there are any worn or damage suspension bushes or components.
In terms of fuel consumption, if you are regularly achieving 60mpg or more then this is actually very good. The average Real MPG achieved by Honest John readers is around 54mpg.
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