Does different front and rear tyres mess up 4 wheel drive?

unwashed potato!

unwashed potato!

unwashed potato!

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I need to get 2 new rear tyres as unfortunately one of them has a slow puncture due and cracking on the outer rim. The treda are still perfectly good, but the puncture can't be repair and now I need 2 tyres annoyingly.

I had a quote for £120 for the cheapest tyres from merityre, but they've said that as its a 4 wheel drive, I should not only get similar quality as the front, but the exact same ones, which come to £200 each. Not something I wish to pay, as I'm barely doing 10 miles a week some weeks, and I'm a very chill Sunday type of driver.

Anyone know if there's truth in what they say?

I am cautious as it's merityre giving the advice.

Unfortunately due to the size of these tyres, no one else local will fit them.
 
Have you tried online mobile tyre fitting? Like tyres on the drive or similar?

I've found them to be basically cheap as using any local firm and never had an issue pick exactly which tyre and they come when it's convenient.

They may be right by the way, which car is it? If it's a modern car with all the ******** electronics you don't need, it might start messing it up if you have different grip profiles. Also I'd never recommend cheap tyres, ever.
 
BUDFORCE said:
Have you tried online mobile tyre fitting? Like tyres on the drive or similar?

I've found them to be basically cheap as using any local firm and never had an issue pick exactly which tyre and they come when it's convenient.

They may be right by the way, which car is it? If it's a modern car with all the ******** electronics you don't need, it might start messing it up if you have different grip profiles. Also I'd never recommend cheap tyres, ever.
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Just tried Tyres on the drive and its part halfords which were stupidly expensive. I've recently used ASDA tyres and they were by far the cheapest i found.
 
I have been running Pirelli on the front and Bridgestone on the back of my BMW 4 series X Drive. This is what BMW gave it to me with so it must be ok in their books. I didn't notice any issues other than maybe slightly less grip on the front than I was expecting considering its rear biased
 
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There can be quite a bit of variation in circumference from one brand of tyre to the next for the same size so you really want to keep them to within a few mm if possible to avoid issues so there is truth to what they're saying. It depends on the 4wd system though, some can 100% be damaged by different tyres front and rear. The Subaru AWD system can be damaged if you do this as the centre diff has to work really hard and you get 'wind up' in it which ultimately will destroy the diff, that's the same reason why you can't tow a AWD car on the back of a recovery truck as you'll just grenade the centre diff, you need to flat tow it or have it recovered on a flat bed.

Other systems like the Haldex based ones i don't think are as fussy as they're not proper full time AWD in the traditional sense so i don't think they suffer from the 'wind up' issues of fully mechanical systems like Subaru and the like use.
 
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Yup, matching circumference is the key, a mate of mine accidently fitted 255/40/18s on the rear of his X trail, typo :D , the front was 225/40/18, needless to say after not many mile he had to replace the rear diff but that is an extreme difference, it should cope with a minor difference but ideally you maintain tyre and wear rates on a 4x4 with tyre rotation and keeping all 4 tyres the same.
 
from physic perspective there is nothing stopping you from having different fronts to rears or even differnet fronts altogether. 4wheel drive will have diff to regulate power and more sophiscated ones will have more diff to each wheels. but basic 4 wheels will definitely have diff going into front axel and rear.

the tyre shop is telling you crap and trying to fleece you bascially.
 
There was a version of the Volvo 850, the cross country I think that when it was released Volvo had never tested it after replacing the tyres so all the tyres were pretty much the same diameter. They only found out after launching it and a few month later when customers were changing tyres on one axle that having different diameter tyres actively destroyed the differential. They had to replace dozens and eventually Volvo developed a fix. Sometimes it does matter, but 99.9% of the time different tyres won't change a damned thing.
 
XeNoN89 said:
I have been running Pirelli on the front and Bridgestone on the back of my BMW 4 series X Drive. This is what BMW gave it to me with so it must be ok in their books. I didn't notice any issues other than maybe slightly less grip on the front than I was expecting considering its rear biased
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Not sure if serious, like a dealer give a @@@@ what tyres are on it, as long as they are legal...
 
unwashed potato! said:
Sure but that's a totally different size.

If he had gotten 225/40/18 but a different brand, what's the difference then?

Mine are 265/35/22 102W
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There can be quite a difference between brands when you actually measure them, that's the big issue. Even within the same make their models can be different, there was a long term review on pistonheads about a subaru years ago and he had 1 tyre replaced due to a puncture and didn't notice it was a different model of Bridgestone despite being the same size the car throw a load of errors as when they actually measured it it was several centimetres different in circumference despite the same size printed on the sidewall.
 
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As someone here has mentioned, it's a big no no with the subaru AWD system
 
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sovietspybob said:
There can be quite a difference between brands when you actually measure them, that's the big issue. Even within the same make their models can be different, there was a long term review on pistonheads about a subaru years ago and he had 1 tyre replaced due to a puncture and didn't notice it was a different model of Bridgestone despite being the same size the car throw a load of errors as when they actually measured it it was several centimetres different in circumference despite the same size printed on the sidewall.
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Sure but isn't that the issue with replacing one? Rather than an issue of replacing the 2 rear ones and then them being a different brand to the front 2?

Or does that still cause a problem because of 4wd?
 
unwashed potato! said:
Sure but isn't that the issue with replacing one? Rather than an issue of replacing the 2 rear ones and then them being a different brand to the front 2?

Or does that still cause a problem because of 4wd?
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Same issues, all 4 tyres need to be the same physical size give or take a couple of mm or you'll run into issues. It is one of the downsides of having an AWD system i'm afraid.
 
Depends on the 4wd system and mainly if it's permanent mechanical 4wd. ie subaru, old audi with the torsen diff. In those cases it's not the type of tyre but the overall diameter that must be the same or as close as possible.
That's why you have to ensure the tread depth is the same all around or it will damage the centre diff.
Haldex and other electronic or part time 4wd systems do not matter as much but it's still recommended.
they also recommend replacing tyres in pairs and never singles
 
thanks. have gone with the exact same tyres in the end. getting installed tomorrow.

came to £165 each, much better than the £220 i was quoted for this exact same tyre else where, but higher then the £50 i'm used to per tyre.
 
unwashed potato! said:
thanks. have gone with the exact same tyres in the end. getting installed tomorrow.

came to £165 each, much better than the £220 i was quoted for this exact same tyre else where, but higher then the £50 i'm used to per tyre.
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£50 per tyre? I think maybe I paid that for my T reg Nissan Almera about 18 years ago. Every tyre I've bought since then has been more than £100 per tyre, although I will admit to sticking to the big brands.
 
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