997 uneven rear tyre wear

[ps01]

I have excessive tyre wear on the inside of the left rear tyre on my 997.1 C2S (no similar problem on right rear or fronts).

I had the tracking done when the tyres were fitted so the camber and toe in on the rear were within the acceptable range. My concern is that the previous set of tyres had exactly the same issue which makes me think maybe something else isn’t right. Car is used regularly - predominantly for commuting up and down the M4 so it leads a relatively gentle life.

Is this something anyone else has experienced? Should I be getting anything else looked at?

Or should I just put a new set of tyres on and have the tracking done again and hope for the best..!

Thanks

Paul

[mollytherocker]

Probably a worn suspension bush. Coffin arm? A specialist can check.

[Trev450]

You say you had the tracking checked when the tyres were fitted, was the camber angle checked as well?

[nxi20]

Rear toe is probably in need of adjustment.

[Pope]

What mileage have the tyres done? How often are the pressure's checked and are there any handling traits you've noticed - steering wheel off centre; drifting on light throttle/over-run??

[Rockster]

mollytherocker said:

Probably a worn suspension bush. Coffin arm? A specialist can check.

I would agree. The alignment is done - obviously - with the car stationary and the settings are selected to ensure proper alignment when the car is moving. The settings assume a certain amount of give to the suspension bushings.

If the alignment is spot on right while the car is on the alignment rack and yet one tire shows uneven wear and inside edge wear is from toe this suggests that wheel is being forced out of position due to a bad bushing.

[majordad]

Perhaps driving on narrow B roads , where the inside edge is rough and or cambered would do this. My rears on the 7gt3 show this type of wear and it s due to roads. Life of rears in my case is 6000 miles max.

[ps01]

Thanks for replies

Rear tyres are now 9,000 miles old. Pressures checked 3 or 4 times over this period. Still a reasonable amount of tread apart from inside left rear.

Tracking report when tyres were fitted showed left rear camber -1.37, right rear camber -1.40, left rear toe 0.13, right rear toe 0.12. All within green (acceptable) range per the report.

No obvious unusual handling traits although I could be missing something if its subtle.

Guess I will take it to Reading OPC or Northway to look at bushes - both close to the office.

[Pope]

I would say that level of wear was normal especially if the rest of the tyre is level across the tread. All of the 997 tyres I see have characteristic shoulder wear - many explanations, ranging from the fact the inner edge of the tread tapers out to zero; the wear bars and tread blocks have a shallower depth to strengthen the block and reduce flex. Worth mentioning the high camber value; rear engined layout and chassis kinematics that place a higher loading on the inner edge of the tyres in normal to high speed use.

See if the specialists concur......

Edited by Pope on Tuesday 8th January 18:38

[Rockster]

ps01 said:

Thanks for replies

Rear tyres are now 9,000 miles old. Pressures checked 3 or 4 times over this period. Still a reasonable amount of tread apart from inside left rear.

Tracking report when tyres were fitted showed left rear camber -1.37, right rear camber -1.40, left rear toe 0.13, right rear toe 0.12. All within green (acceptable) range per the report.

No obvious unusual handling traits although I could be missing something if its subtle.

Guess I will take it to Reading OPC or Northway to look at bushes - both close to the office.

One thing that I forgot to mention is that for cars without LSD and in the case of cars driven on the left hand side of the road, the inside (left) rear tire can wear faster than the right rear tire. The reason is when making a left hand turn the inside rear tire is lightly loaded and will slip if the driver is too heavy on the gas going around the corner.

But have a qualified shop check the bushings. While bushing trouble is rare it can happen.