RWD tyre question

[Rroff]

Starting depth on the tyres is ~7.5mm, manufacturers tolerance is for up to 2mm difference without any significant effect front to back so 5.5mm is fine, not really applicable here but systems like 4Motion have a ~2mm tolerance per axel, xDrive has a rolling circumference tolerance of up to 1% difference (this should be adhered to if you care about the lifespan of the components - though it won't cause a catastrophic safety issue).

Beyond ~2mm difference front to back you will start to see oversteer or understeer issues in wet conditions though in the dry it generally takes a bigger difference to be an issue.

 

[Armageus]

Beyond ~2mm difference front to back you will start to see oversteer or understeer issues in wet conditions though in the dry it generally takes a bigger difference to be an issue.

Will?

That's quite a bold statement.

I can categorically say I've never experience an understeer or oversteer situation even in the wet due to differences in tyre wear (and I normally end up replacing 2 tyres at a time, and have never rotated tyres to even out wear).

(*I have experienced both understeer and oversteer, but normally due to some overly "enthusiastic" driving, nothing to do with tyre tread depth)

 

[Jonnycoupe]

Its more the consquence of aquaplaning thats the concern for road users.

 

[deviation]

Will?

That's quite a bold statement.

I can categorically say I've never experience an understeer or oversteer situation even in the wet due to differences in tyre wear (and I normally end up replacing 2 tyres at a time, and have never rotated tyres to even out wear).

(*I have experienced both understeer and oversteer, but normally due to some overly "enthusiastic" driving, nothing to do with tyre tread depth)

It's also worth noting that an open differential can cause uneven tyre wear, especially if one wheel receives more torque than the other, which leads to faster wear on said tyre. This is often occurs during turns or on uneven surfaces.
Alpina for example, don't use LSD's as standard based on their customers preference, as with AMG's, the LSD is always optional on most of them.
And that doesn't cause any real world issues... Otherwise we'd all have LSD's or a live rear axle

 

[Rroff]

Will?

That's quite a bold statement.

I can categorically say I've never experience an understeer or oversteer situation even in the wet due to differences in tyre wear (and I normally end up replacing 2 tyres at a time, and have never rotated tyres to even out wear).

(*I have experienced both understeer and oversteer, but normally due to some overly "enthusiastic" driving, nothing to do with tyre tread depth)

In the right (or wrong) conditions you will start to get oversteer or oversteer in conditions that closer matched tyres would cope with fine - won't mean you are fishtailing around all over the place just because of a bit of rain and a few mm difference. Especially in shorter wheelbase smaller vehicles.

 

[jaybee]

I regularly see the most toxicity on this forum in the motors section. Not really any need to be so aggressive and toxic.
@Nasher only said that it might understeer a bit. That's not technically wrong. OK so this is extremely unlikely outside of a track day at the limit but still.
I've had lift off oversteer in my Ford S-Max due to worn rears. A 7 seater people carrier. I'm not sure why that would be so disputed due to tyres being worn.

 

[deviation]

I've had lift off oversteer in my Ford S-Max due to worn rears. A 7 seater people carrier.

Please can someone recreate this with AI, preferably with eurobeat playing

 

[jaybee]

I can categorically say I've never experience an understeer or oversteer situation even in the wet due to differences in tyre wear

Good for you. I have.

 

[deviation]

Good for you. I have.

Do you run cheap brand/eco tyres? How often do you check tyre pressures, have your alignment checked and replace things like bushings, ball joints etc?
Or do you wait until they're advised to be replaced on the MOT - not trolling, I totally get that some people just wait to be told. But it all adds to random/sketchy handling occurrences.

 

[Rroff]

I've had lift off oversteer

Hopefully not speaking too soon but in nearly 25 years of driving, including a limited amount of track, I've not experienced lift off oversteer of any consequence - definitely never had snap oversteer happen.

 

[JonRGV250]

Lift off oversteer is ridiculously easy to do on purpose for ***** and giggles or easy to do via poor driving (that’s not aimed at anyone).
Blaming it on the tyres is a bit daft imo.
Just to add, I’ve done thousands of miles on track and watching the front wheel drive boys doing it never didn’t amuse me.

 

[jaybee]

Do you run cheap brand/eco tyres? How often do you have your alignment checked and replace things like bushings, ball joints etc, or do you wait until they're advised to be replaced on the MOT - not trolling, I totally get that some people just wait to be told. But it all adds to random/sketchy handling occurrences.

You are literally teaching me to suck eggs if you want to go down that road. I've worked on all my cars/bikes over the years and I'm just purely saying, tyre wear differences between front and rear absolutely can account for under/over steer. I've had it happen. Not really that hard a concept to understand. To call people out above for pointing that out - no matter how unlikely when the fronts still have 5mm - is just harsh and frankly wrong. I say fair play for pointing out a potential safety issue.

 

[Armageus]

I regularly see the most toxicity on this forum in the motors section. Not really any need to be so aggressive and toxic.
@Nasher only said that it might understeer a bit. That's not technically wrong. OK so this is extremely unlikely outside of a track day at the limit but still.

No it's not technically wrong, but it's extremely unlikely to be noticeable to any consequence.
However someone could easily look at that and go, "Understeer - oh no that's bad I should buy 4 tyres instead of 2", and end up spending plenty of unnecessary money. Much like the frequent suggestions of "you must buy the latest Pilot Sport otherwise you'll be dead in a ditch", despite them driving a 1.2 litre Honda Jazz 5 miles a week.

I've had lift off oversteer in my Ford S-Max due to worn rears. A 7 seater people carrier. I'm not sure why that would be so disputed due to tyres being worn.

You can't definitely say it was due to worn rears. You can instigate lift off oversteer in almost all front wheel drive cars very easily.

 

[Rroff]

Lift off oversteer is ridiculously easy to do on purpose for ***** and giggles or easy to do via poor driving (that’s not aimed at anyone).
Blaming it on the tyres is a bit daft imo.
Just to add, I’ve done thousands of miles on track and watching the front wheel drive boys doing it never didn’t amuse me.

It kind of worries me as I've done many 100s of thousands of miles including some crazy stuff and not experienced any consequential amount of it so no experience of how to deal with it if it does happen :s back in the day watching my friends in their Novas, Saxos, Pandas, etc. lose it to lift off snap oversteer in the rain and just wondering how as I've never had it happen to me.

 

[deviation]

You are literally teaching me to suck eggs if you want to go down that road. I've worked on all my cars/bikes over the years and I'm just purely saying, tyre wear differences between front and rear absolutely can account for under/over steer. I've had it happen. Not really that hard a concept to understand. To call people out above for pointing that out - no matter how unlikely when the fronts still have 5mm - is just harsh and frankly wrong. I say fair play for pointing out a potential safety issue.

So this family wagon is brand new then? Or frequently maintained with all OEM parts before they're flagged as an advisory, and runs premium tyres all round, all replaced at the same time, yearly, does it?
If not, then I stand by what I said, it can occur due to a multitude of factors, and not solely black and white as you try and paint.

 

[Jonnycoupe]

Panic cos you are going to fast, maybe you never drive fast

 

[jaybee]

No it's not technically wrong, but it's extremely unlikely to be noticeable to any consequence.
However someone could easily look at that and go, "Understeer - oh no that's bad I should buy 4 tyres instead of 2", and end up spending plenty of unnecessary money. Much like the frequent suggestions of "you must buy the latest Pilot Sport otherwise you'll be dead in a ditch", despite them driving a 1.2 litre Honda Jazz 5 miles a week.

Completely understand your point, but this is a BMW M2. A performance car with a lot of power. I think it would be prudent to discuss how tyres may affect handling at the limit, since this is car which is usually bought to be driven near the limit.

You can't definitely say it was due to worn rears. You can instigate lift off oversteer in almost all front wheel drive cars very easily.

This was due to worn rears. You weren't there. Don't embarrass yourself.

 

[Kenai]

I've never had it happen to me.

You've clearly never been trying hard enough into a decent bend

 

[jaybee]

So this family wagon is brand new then? Or frequently maintained with all OEM parts before they're flagged as an advisory, and runs premium tyres all round, all replaced at the same time, yearly, does it?
If not, then I stand by what I said, it can occur due to a multitude of factors, and not solely black and white as you try and paint.

I never said it couldn't occur due to multiple factors though.

 

[Rroff]

Panic cos you are going to fast, maybe you never drive fast

I've done a bit of everything in my time, though these days I tend to stick to a sensible speed for the limit and conditions, usually close to if not the speed limit.