Turns out the alignment on the front wheels was out on my car, so the inner shoulders are goosed. The rest of tread is fine. The back tyres have 6mm ish of tread left on them
I assume replacing both front tyres with the same make and model and keeping the old ones won't be an issue..specifically aski g because it's a 4wd car?
Ta
Far from my field of expertise but isn't there the risk that different effective rolling circumferences bugger you the drive between the two axles?
Also interested in the correct answer just out of interest.
I think it depends on the car - some require it some don’t.
Interested too. I'm in a similar situation. Our Subaru has 4 half-worn tyres, one has a nail in it. Going in this week for a second go at repairing it, but might need a new one.
Subaru garage always warns me that all 4 must have the same tread depth. The tyre shop says rubbish. The manual does say...
'If all four tires are not the same size/circumf/speed/load/make/model/wear there is a possibility that it may lead to serious mechanical damage to the drive train of your car...'
Expensive nail if I follow that advice to the letter.
Meh
Ain't nobody replacing perfectly good rear tyres just because the fronts are a bit worn. Does any car wear down all 4 tyres evenly?
Mine seems to. All four had 6mm tread at the last service.
Spoke to the missus. The cupra garage told her when they checked all 4 that only front 2 needed replaced, so I'll happily go with that!
I could see why at the extremes it would matter but a few mm? Surely at that point even different pressures would be a problem?
The car will have a centre diff. It copes fine with the front wheels turning at different speeds to the rears when they are steering, so will cope fine with minuscule differences in circumference.
It only becomes an issue when there is no centre diff - such as old school pick ups and farm ATV's where you can only engage 4wd when you're on very loose surfaces which will allow for different rotations due to slippage
'If all four tires are not the same size/circumf/speed/load/make/model/wear there is a possibility that it may lead to serious mechanical damage to the drive train of your car...'
i.e. we have a escape clause for our shitty warranty
Not sure on 4wd but 'new' advice on FWD is that the better grip goes on the rear - if the car loses grip then it's more natural to save a FW slide than a RW
New - as in I was told that the good went on the front until recently, not sure if I was ever right or when the opinion changed. I've been driving 39 years (not continuously)
No idea on a 4WD though.
Does it have permanent 4wd? If a haldex or similar part time system there is no need to worry. And if permanent then the difference between new tyres at 7 or 8mm and part worn at 6mm is very unlikely to be significant.
If it's permanent 4wd then the centre differential bevel gears will be rotating to account for the rolling radius difference - it would only be a problem if you were on the world's straightest road driving flat out to cause problems.
It's also why a 4wd car shouldn't be rolling road brake tested as it really spins the centre diff up which can cause the bevel gears to seize {in theory}
Not sure on 4wd but 'new' advice on FWD is that the better grip goes on the rear
Same advice applies to any vehicle you drive on public roads - grippier tyres on the back.
Yep, new on the back - helps with controlling designed understeer tendencies; taking your foot off the pedal allows the rear to grip and correct (hopefully). Good article on it here:
taking your foot off the pedal allows the rear to grip and correct (hopefully).
205gti wants a word 😀
That "new on the rear" advice obviously hasn't reached Aberdeenshire yet as our local tyre place still puts the new pair on the front (whether FWD or AWD). The front tyres do all of the steering and most of the braking and I can't remember the last time I lost the rear on a FWD car. So I can understand why people think the tyres that grip best should go on the front, even if it is wrong.
I have a Vulva (ahem) and 'they've ' told me a difference of >4mm front to back is enough to screw up the AWD Haldex. It could be a Dealer's old wive's tale but I don't know enough about it to pushback with any certainty. When I last checked, my fronts were ~1mm more worn than the rears so I rotated front to back like in the olden days 🙃
I can't remember the last time I lost the rear on a FWD car
I can and it was a) entirely my fault and b) scared the crap out of me as I ended up backed into the verge between a tree and a telegraph pole. Lift off oversteer whilst driving like a tit many, many years ago.
I can't remember the last time I lost the rear on a FWD car
Yesterday morning for me.
Some chump decided to join the roundabout I was already on and my lifting off on greasy/frosty/wet pre-dawn tarmac had my elbows and the ESP (Mostly the ESP, I'm sure) scrabbling to keep me in the direction of Monmouth.
BMW and Audi recommend you change all four because it screws up the transfer box
I had to change my front because of pothole damage. My tyre man suggested just doing the front axle - so two new tyres.
Haldex shouldn't care. It's effectively a constantly slipping wet clutch pack whose natural phase is disengaged. Anything with a straight viscous coupling, viscous coupling locking or torsen centre diff might care though. Basically if its a VW / skod / seat / RS3 , it'll be fine. Freelander (though I think they are haldex AND a viscous unit) Audi A4/5/6, Alfa Q4, BMW XDrive it might cause issues.
So I can understand why people think the tyres that grip best should go on the front, even if it is wrong.
So can I. I was an idiot boy racer in my youth and thought that I had the driving skills of a god. Therefore, a bit of oversteer was the way to go so grippier tyres on the front. Totally stupid on public roads, but it seems intuitive to have the best tyres on the front. Intuitive, but wrong.
Subaru garage always warns me that all 4 must have the same tread depth. The tyre shop says rubbish.
I bet the tyre shop aren't going to put that in writing.... in which case it's advise worth exactly what you paid for it.
My car also says that front and rear should be the same and the cost of risking not doing so isn't worth it. So, seeing as it wears the rears slightly quicker than the fronts, a mid-life front/back swap takes place.
Reading that in the US, tyre shops will shave a new tyre to match the tread depth of the others on an AWD vehicle, so must be something in it.
