labrat

In all my recent fun, I forgot to ask you guys something. At the last service, I asked for a wheel alignment as well as tyre rotation. OK, I forgot to ask previously, and I should have asked in the past. Not out very much at all, but I was told that all tyre were wearing on the inside edge, and I probably should replace them within the next 6 months (say 5000km). Well, I guess that nearly 50,000km won't be too bad, but I would have liked to have done better, especially since there appears to be plenty of tread. Note that there is no scalloping, and wear across the tread appears quite even.

When I replaced the OEM tyres 3 years ago, there wasn't any choice in 225's and I went for 245's to get the same rolling distance. I found I had to put the pressure up from 230kPa (33psi) to 260kPa (38psi) to get rid of squirming, and hopefully restore a flat profile on the road. Now some questions for the tyre and wheel experts. Is the wear on the inside caused by:
1. Under-inflation. Could even 260kPa be too low, especially with a tyre that is on the limit for an 8" wheel? Could the combination of camber, largest tyre on an 8" wheel and under-inflation cause the inside edge wear?
2. Or simply, I've neglected the suspension adjustment and the camber has increased with car age.
3. Or is it simply the tyre is too wide for the car?

I must say I like the look of the 245's on the car, but I might have to go to a 235 if the 245 is plain unsuited.

The Mazda dealer is trying to convince me to go to 235's, telling me that this is the recommended replacement size. I mentioned the Potenza 225's (what's happened to them?) and he said they scallop. Hmmm.

thisllub

50000km !!!
Mine are illegal now and I have done 21000.
I am shopping at the moment and it is an expensive prospect.
What are you using now?

MACCAA

Under-inflation isn't the problem with wear on the inner edges.It's either toe in or out,or too much neg camber.
The Bridgestones have a reputation of inner wear,but personally my car never had the problem.
If you run around -1.25 camber all round,and zero toe front and back,it should be OK.
Cheers
Len

Revolver

Labby's running Fulda's from memory.

I don't reckon tyre pressures or size are the problem. I think you need to check out camber, etc as Len says.

If it's any help, I've been running 235's on 8.5 rims for ages now and the tread wear is very even. As for diameter difference - it's only about 2-3km/h more optimistic on the speedo, so think of it as an anti-booking device.

takahashi

Lens is correct. Bridgstone is **** in the inside in terms of wear.

Revolver and I can tell you. I have -2.5 camber in my car front and rear and I think the inside wearing better than the outside on our Michellin PS2!

Revolver

Agreed. The upfront ask for PS2's may be a bit daunting but the grip and life you get out of them really is good value.

auzoom

I will also agree 100% with Len. But my guess is the toe is the main culprit.

DrGonzo

What's scallpoing? Is that another word for tramlining?

auzoom

http://www.kaltire.com/commercial/me...es/cupping.php

DrGonzo

Thanks, I'd never heard of scalloping before.

LOL at the final paragraph:

Cronullarx8

Taka - how do you get -2.5 deg on the front? Std I can only get about 1.3deg

auzoom

1.3 as in 1 degree 30 min (1.5) or 1.3 as in 1 degree and .3 of a degree (1.18)?

Anyway, trick is that you have to go beyond what the adjuster washer does. You should be able to get 2 deg.

Cheers

Andrew