What causes tyre wear in the middle of a rear tyre

[madras]

What is the reason for rear tyres on a RWD car wearing out in the middle long before the edges? Pressures have been correct, or if anything, under inflated.

Should I now swap them over to the fronts as they are more likely to wear around the edges?

Thanks

[apache]

Have you fitted motorcycle tyres by mistake?.........easily done I'm sure

[stew-typeR]

over inflated

[apache]

stew-typeR said:

over inflated

you didn't read it did you

[madras]

In the evo M5 (E34) buying guide it says "Worn centres of the rears could mean the rear sub-frame bushes have collapsed"

[GreenV8S]

apache said:

stew-typeR said:

over inflated

you didn't read it did you

I know he said they aren't over inflated, but that's the only reason I can think of for it.

[apache]

GreenV8S said:

apache said:

stew-typeR said:

over inflated

you didn't read it did you

I know he said they aren't over inflated, but that's the only reason I can think of for it.

me too

[GreenV8S]

Maybe the wear is occuring under different conditions to the ones where you're checking the pressure. Perhaps the tyres are heating up and increasing the pressure more than expected, or expanding with speed, or something like that?

[smb]

some tyre designs do not keep a constant flat profile on the road , and at speed 'balloon up' creating a higher profile in the middle of the tyre, and hence greater wear there. Not all tyres have the same structural strength to maintain their shape.

[combemarshal]

Another one, Over inflated!
The temps wont be the same all day, and I bet your not on Standard tyres/wheels, where did you get the presures from?
Different tyres need different PSI!

[madras]

combemarshal said:

Another one, Over inflated!
The temps wont be the same all day, and I bet your not on Standard tyres/wheels, where did you get the presures from?
Different tyres need different PSI!

ok look, is it impossible to post on PH without someone assuming it's always the obvious answer?? I wouldn't have bothered if I thought that's all you could come up with, clearly increased pressure will force the centre of the tyre to be more prominent on the road surface

i always check pressures when cold, and if you checked them when hot you would end up under inflating them! P=K (T/V), K - constant, ideal gas law

Could it not just be hard acceleration in a straight line? Pressure were form a Michelin foot pump (won the autoexpress test for consistent accuracy and precision) that is frequently tested on other equipment/tyres for accuracy.

The car is on standard wheels and standard tyres

[Sam_68]

madras said:

ok look, is it impossible to post on PH without someone assuming it's always the obvious answer??

I'm sure everyone is only trying to help.

Perhaps the problem is that the obvious answer is the only logical one in this case. I can't think of anything apart from over inflation or tyre carcase structural characteristics that would lead to excessive wear in the centre of the treads.

Shot bushes wouldn't do it - they'd wear the tread on one side of the tyre; neither would tyre growth from acceleration or sustained high speed (unless you spend all your life lapping the Millbrook Bowl at 180mph).

Just because it's obvious, doen't mean it's wrong!

[combemarshal]

madras said:

combemarshal said:

Another one, Over inflated!
The temps wont be the same all day, and I bet your not on Standard tyres/wheels, where did you get the presures from?
Different tyres need different PSI!

ok look, is it impossible to post on PH without someone assuming it's always the obvious answer?? I wouldn't have bothered if I thought that's all you could come up with, clearly increased pressure will force the centre of the tyre to be more prominent on the road surface

And theres your answer.
But have you checked them when hot?
If not how do you know what presure they end up at after a bit of thrashing, don't forget recomended presures are for road use and biased towrads economy.
Try nitrogen.

Thats the end of any more ideas on this thread

Edited by combemarshal on Wednesday 28th February 13:26

[taffyracer]

Are you the foot pump is accurate, have you compared to it a decent quality tyre pressure gauge? I'd say that this might be the problem, i've seen loads of different readings from different gauges, its not uncommon

[madras]

combemarshal said:

madras said:

combemarshal said:

Another one, Over inflated!
The temps wont be the same all day, and I bet your not on Standard tyres/wheels, where did you get the presures from?
Different tyres need different PSI!

ok look, is it impossible to post on PH without someone assuming it's always the obvious answer?? I wouldn't have bothered if I thought that's all you could come up with, clearly increased pressure will force the centre of the tyre to be more prominent on the road surface

And theres your answer.
But have you checked them when hot?
If not how do you know what presure they end up at after a bit of thrashing, don't forget recomended presures are for road use and biased towrads economy.
Try nitrogen.

Thats the end of any more ideas on this thread

Edited by combemarshal on Wednesday 28th February 13:26

they are 5psi higher when warm, as you'd expect. Tyre pressure are supposed to be checked when COLD, not checked after a thrashing.

Thanks for your suggestions guys, I'll check the wear out on a new set.

Edited by madras on Thursday 1st March 08:30

[GreenV8S]

madras said:

they are 5psi higher when warm, as you'd expect. Tyre pressure are supposed to be checked when COLD, not checked after a thrashing.

That depends whether the reference pressure you're using is a hot or cold figure. The figures you're likely to be quoted for an ordinary road car on standard tyres will almost certainly be cold ones.

[splatspeed]

spinning the back wheels

i used to get this on my mr2 turbo

i play a lot

middles allways go first

and lasted 5000 miles

[combemarshal]

GreenV8S said:

madras said:

they are 5psi higher when warm, as you'd expect. Tyre pressure are supposed to be checked when COLD, not checked after a thrashing.

That depends whether the reference pressure you're using is a hot or cold figure. The figures you're likely to be quoted for an ordinary road car on standard tyres will almost certainly be cold ones.

And Tyres aren't meant to be thrashed!
What V8s said, speak to the tyre company, they will probably be more than useless, goodyear are!

[madras]

GreenV8S said:

madras said:

they are 5psi higher when warm, as you'd expect. Tyre pressure are supposed to be checked when COLD, not checked after a thrashing.

That depends whether the reference pressure you're using is a hot or cold figure. The figures you're likely to be quoted for an ordinary road car on standard tyres will almost certainly be cold ones.

yes as said in earlier post, they are COLD

[madras]

splatspeed said:

spinning the back wheels

i used to get this on my mr2 turbo

i play a lot

middles allways go first

and lasted 5000 miles

that makes more sense. no geometry problems then. thank you.