HighlandPete

Sorry if it is not clear. Pictures are from same car, same axle, same geometry, over same 'mixed' period of 35k miles. Why would one wear flat, the other taper across the tyre? Engineering logic says the wider tyre will show more wear. Or we are seeing our dear old 'Run-Flat' exhibiting another strange feature. I'm hoping to take this thread further, into why the very severe wear occurs with the current run-flats and normal rubber. If there is no logic to the problem posed, I can understand why some have the opinion there is no logic to the severe wear patterns. I'm hoping Tony will have some comment. HighlandPete

There is so much to discuss here, with all the recent severe inner tyre wear and cracked rims on the latest 3-series cars, particularly the 19†run-flat shod wheels. I have my own opinions, but would welcome discussion. I’ll start a bit further back in time. My last BMW was an E39 540i touring, running M-Tech suspension and fitted with Style 32, 17†rims, unusual for a touring, had a staggered setup 8â€/9†x 17†rims running 235/45 & 255/40 tyres. Tyre wear was very good on the rear with self levelling air suspension, but took accurate pressure settings to balance the wear across the tyre and the dreaded inner edge wear. I’d get about 20k miles from Dunlop SP 2000E’s and would be down to about 3mm across the tyres with the inner edges just 'almost' knocked off. The rear 32’s were ET26, and running 18.7mm more offset inside, than standard 8†rims for the rear. Now I’m running (from new) an E91 330d SE touring, on standard suspension, running standard 225/45 R17 all corners, style 160 with Bridgestone Potenza RE050A (ll) run-flats. The picture shows wear at 15k miles. I’ve a second OEM wheel set, style 161, 8â€/8.5†with normal rubber, for reasons we can imagine, but that’s another discussion. Now the offset for the 8.5†rear is ET37, giving 9.35 mm more offset inside. The wear on the 225/40 R17 Goodyear’s is for 20k miles. Try and get your heads around the different wear patterns. Both sets have been on and off the car over the past 35k miles, all on the same geometry, driving the same sort of roads and driving style. You’ll note the Bridgestone’s wear towards the outside, but also has the inner ‘camber wear’. The inner and taper wear were there from early on. Note the tyre at 8 – 9k miles. Tyre pressure is critical to get the wear balance right, not to lose the tyres too early. The Goodyear’s were very even across the tyre, as can be seen, just starting to lose the inner edge. (Left side of the picture). What is going on here, geometry? Is it in the tyres? Or is there much more to it... how we corner for example? I’d welcome any comments on this, before we look at the rapid wear on some models today. Much more to say, but trying to keep it limited to start with. HighlandPete

I knew I had a link somewhere. Part way down the page is the detail and some pics'. http://www.topspeed.com/cars/renault/2007-...rt-ar32093.html HighlandPete

Virtually the same system as the Ford RevoKnuckle, as fitted to the RS Focus. A more elegant bit of design than Fords simple engineering, IMO. http://www.not2fast.com/chassis/revoKnuckle.pdf HighlandPete

Sounds interesting... as an engineer I'd like to get involved in discussiong this subject. I'll put my thoughts, experiences and photos together and start a new thread. Thanks for the welcome. HighlandPete

Hi! new to your forum. Found the site last evening, and delighted to find some very good technical expertise. So thought I'd have a look at the forum. I'm researching BMW tyre wear. Happened to find this thread. And here we have pictures, so similar to BMW rear wear. I'm a veteran BMW user, so very familiar with rear inner wear, but the latest rash of RFT tyre wear and cracked rims has got me looking to why the camber wear is so severe, particularly on the E92/3 models. Cracked rims is another subject... I'm very interested in any views on this subject, is it just geometry, as the tyre wear illustrated on this thread, or is there more to it? For example for the BMWs, is the stiff side wall also making it worse during cornering. I sense the speed of some premature failures from new, is involving some sort of scuffing. To take it further, perhaps I should start a new thread on the BMW issues. Don't want to barge in as a new boy. Sorry if I'm taking the thread slightly off topic. HighlandPete