rear tyre wear: inside edge disappears!

[alan.timms]

Hi,
A friend of mine has a "facelift" 75 diesel auto Tourer with a strange tyre problem. The back tyres wear on the inside edge - starting with 8mm tread, by the time the tyre is down to 7mm, the inside edge has worn at 45 degrees, so an inch in from the edge there is 7mm, then a chamfer taking the rubber away to the core an inch in and down. There's no obvious bearing or suspension fault, the garage says there is no adjustment on the back wheels, and the tracking is correct at the front. It looks like a piece of bodywork has rubbed it away, but there's no sign of that actually happening. Help, please!

[rover54]

Hi,
A friend of mine has a "facelift" 75 diesel auto Tourer with a strange tyre problem. The back tyres wear on the inside edge - starting with 8mm tread, by the time the tyre is down to 7mm, the inside edge has worn at 45 degrees, so an inch in from the edge there is 7mm, then a chamfer taking the rubber away to the core an inch in and down. There's no obvious bearing or suspension fault, the garage says there is no adjustment on the back wheels, and the tracking is correct at the front. It looks like a piece of bodywork has rubbed it away, but there's no sign of that actually happening. Help, please!
Tracking is out. On 75's rear suspension can be adjusted as well as the front. You need to get it laser aligned or use a slip pad such as this http://www.ebay.co.uk/itm/Gunson-Trakrite-Wheel-Alignment-Tracking-System-Part-no-G4008-New-/180882350285?pt=UK_Measuring_Tools_Levels&hash=item2a1d6da0cd

Adjustment is via item 5 which has slotted holes to swivel suspension

http://www.rimmerbros.co.uk/ItemImages/Large/GRID001553.gif

http://www.rimmerbros.co.uk/Item--i-GRID001553

[alan.timms]

Tracking is out. On 75's rear suspension can be adjusted as well as the front. You need to get it laser aligned or use a slip pad such as this http://www.ebay.co.uk/itm/Gunson-Trakrite-Wheel-Alignment-Tracking-System-Part-no-G4008-New-/180882350285?pt=UK_Measuring_Tools_Levels&hash=item2a1d6da0cd

Adjustment is via item 5 which has slotted holes to swivel suspension

http://www.rimmerbros.co.uk/ItemImages/Large/GRID001553.gif

http://www.rimmerbros.co.uk/Item--i-GRID001553
Instant service! Thank you for the advice. Why does it take the corner off, not wear the whole tread surface at an angle?

[rover54]

Instant service! Thank you for the advice. Why does it take the corner off, not wear the whole tread surface at an angle?
Its all to do with the slip angle and the loading on the tyre. Imaging pushing something along the floor, the leading edge will tend to wear more as it tries to dig in as there is greater point loading. With wheels with excessive tow in/out you effectively have a leading edge as the tyre is scrubbling along as well as turning.