different tread same axle?

[bobjebb]

Just wondered as a girlfriend came to visit at the weekend and I noticed. Is this ok?? They are the both michelin pilots. Thanks

[harry]

I wonder if she goes out on the town with different shoes on too? or perhaps this is a subtle indication that her collar 'n' cuffs don't match

AFAIK its best to have matching tyres and tread depth on drive axle to promote stability and maintain tyre/traction behaviour. especially so with our Quattros but perhaps just as relevant on a beemer with all the power going thru the back wheels.

[simple1]

I had this problem when a brand new pilot 1 got a nail in it, new Pilots are symetric, and was advised to replace both by local tyre company.... very expensive puncture... BMW backed up the advice

[bobjebb]

Harry, no worries. Her collar and cuffs do match. She has blond hair and a blond fanny. I know, I have seen them.

Anyway, it was just that they said to her it was fine at the garage, and I was a little sceptical, thats all, but as long as it's not dangerous, cos this bird needs all the help she can get when she's behind the wheel of a car.

Thanks

[s4woody]

She has blond hair and a blond fanny. i take it by fanny u mean hair and not skin...

[harperboy]

She has blond hair and a blond fanny. i take it by fanny u mean hair and not skin...

Now that is off topic!

[simple1]

But about the most interesting thing that has been posted all day Ho hum

[shineydave]

Her collar and cuffs do match

presumably you don't mean they match the tyres. one bald, lol

[Dippy]

I both agree and disagree with Harry.

I agree that for a RWD BMW, the significantly different tread pattern is bad news, particularly in the wet.

I disgree that the situation is worse for Quattro. Since it is 4WD, the difference in tread pattern has less impact. This is true for tread depth too. If anyone wants to come back with that old chestnut about "transmission wind-up", please bring the evidence this time

[harry]

Dippy I wasn't indicating it was worse for quattro but just perhaps it adds more unecessary stress on the centre diff (from reading earlier threads on here)

Is this what you are refering to by "transmission wind up"? If so then I have no evidence of this per se, only what I've read on here and I change her boots in fours regarless

I'd be keen for some clarity too TBH

[bobjebb]

I agree that for a RWD BMW, the significantly different tread pattern is bad news, particularly in the wet.

so should they be better on the front?

ta

[SimonS4MTM]

Depends how well she wants to brake in the wet!

[TarmacTerrorist]

I disgree that the situation is worse for Quattro. Since it is 4WD, the difference in tread pattern has less impact. This is true for tread depth too. If anyone wants to come back with that old chestnut about "transmission wind-up", please bring the evidence this time

1. For a modern rwd car with a bit of power under the hood, I would run the same tryes all round epsecially on the rears (rain, dry, whenever). The missus has a fwd 1.0 ltr Yaris that when she tw*ts it up the kerb I replace one trye at a time with whatever they have on the shelf.

2. Old chestnut?? wtf??, I can assure you that the car did not like running different tyres front to rear on the rs4. I could feel (and hear) very bad transmission wind-up coming through the car from the centre diff, simple as that. Are you questioning my abilty to read what it happing to the car through the feel in my arse when I change something around on it??? This problem was appartent the momment I swapped them around on the car thankyou very much!!

I've been thinking about what could actaully be causing this problem and I would suggest the trye tread pattern has ALOT to do with it !! probably in the way that the 2 different cut patterns will shift and react under high loads on the road surface. I found the car felt worse (as gumball posted) when accererating in a straight line, no corners involved what so ever.

Other things it could possibly be are differing r/dia, but that doesnt stand when changing just 2 tyres of the same make, you just dont get the problems like 2 different tyres has.

Trye wall stiffness?? Possible....Centripital forces will have an effect on the shape of the tyre, the stiffer the wall the more it will be able to hold its shape i would have thought.

Differing compounds and hardness of rubber?? Again very possible.

However, I still favour the block shift thoery and would suggest that its effect are worse when both sets have plenty of rubber left on them

[TarmacTerrorist]

Yes, blonde fanny. Very nice.