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MG MGA - Uneven rear tire wear

Hi,

I have uneven wear on both rear tires where the outside is wearing quicker then the inside of the tire. I’ve asked the tire shop if they could adjust something on the car but they told me there is nothing to adjust.

Has anybody encountered the same problem and is there something to do about it ?

Koen
Koen Ackermans

Koen

Not experienced that. What tyre pressures are you running?

Steve
Steve Gyles

Hi Steve,

I have 2,0 bar on them.

Koen
Koen Ackermans

Koen

That's 29psi in our money. Perhaps a little higher than many of us run, but I would not have thought that would induce the sort of wear you are describing, but there again I am no expert. I have 27psi all round. Some even suggest as low as 25 on the rears.

Perhaps you enjoy cornering hard and letting the back swing out!

Steve
Steve Gyles

Hi Koen,
How long have you had the car? A bent rear axle case can have this effect - I know that from experience.

All the best,
Phil
p parmenter

Running wide tires on narrow wheels will have that affect. I had exactly that problem when running 195-60-15 race tires on 4-1/2 inch wide wheels (required to stay in Stock class with SCCA) The problem is caused by tire sidewalls that are not parallel.

Ideally the rim width should be about the same as the width of the tread patch on the pavement, so the tire sidewalls stand essentially straight up and parallel. When the sidewalls flex during hard cornering the tread stays flat on the pavement.

When the rim is too narrow for a wide tire, the tire bead is pulled inward making the sidewalls form a trapezoid. During hard cornering the tread is pushed sideways. This causes one sidewall to stand up straighter while the other one gets shorter. The taller more vertical wall presses down hard on the tread while the shorter leaning wall lifts the tread off the pavement. End result is severe wear on the outside shoulder of the tire and very little wear on the inside shoulder. When the outside shoulder of the tread wears through to the structural tire cords the tire is trash.

The solution is wider wheels for wider tires. Pay attention to the tire manufacturer's recommendation for wheel width.
Barney Gaylord

Barney,
Attached is a photo of my tyre that seems to have performed contrary to your experience with large tyres on small rims.
This is 195/55/15 Dunlop Direzza tyre running on 4.5" wide 60 spoke wheels on my A roadster. All 4 tyres show the same wear pattern.
These are my competition wheels (sprints, hillclimbs, motorkhanas, etc) operating at 26 psi cold.
(I got my money's worth out of this set!)
Mike

Mike Ellsmore

Hi,

I have my car for over ten years now, drive it regularely. Tyre size is 165 HR 15, Vredestein Sprint Classic on wire wheels.

Phil,

How did you fix the axle ?

Koen
KMK Ackermans

I have been itching to say something silly about "Ackerman steering geometry" and rear wheel steering but so far I have managed to restrain myself.
Colyn :-)
c firth

http://en.wikipedia.org/wiki/Ackermann_steering_geometry
For those wondering about Ackerman geometry!
Mike
Mike Ellsmore

I would put a modern optical aligner on tthe rear wheels and check chamber and toe in/out - should both be zero.
Mike Ellsmore

This thread was discussed between 02/12/2013 and 08/12/2013

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