Continental run flat tyre failure on Mercedes

After 8500 miles (from new) I noticed a rumbling coming from the rear nearside tyre on my C250 AMG Line estate. The tyres are Continental 255/35R19Y run flats. When I took the car to my local tyre suppliers they noted that both rears were worn on the inside edges. Removing the wheels revealed a large bulge on the nearside tyre and when they were taken off of the rims and inspected internally it looked like they had been cut around the inner edge with large chuncks of rubber missing. Continental took the tyres back for inspection, have allowed a 40% rebate for unused tread but have not said what caused the premature failure. I have since, this week, heard of a B class on Continental run flats with exactly the same problem. Has anybody else had this experience or any ideas what caused it?

Asked on 18 September 2015 by Gordonmpd

Answered by Honest John
Firstly these are pretty stupid tyres for Mercedes to fit to what is after all a diesel station wagon. 35 profile will always be a lot more vulnerable than 50, 55 or 60 profile. Secondly, this type of damage is usually caused by straddling metre wide speed humps, which means the weight of the car is forced down over two sloping edges and causes massive abrasion to the inner shoulders of the tyres. So only ever navigate a metre wide speed hump one wheel over the centre and one wheel on the flat.
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