[yugrac]

Originally Posted by Mgrae456

A run flat would have made no difference they actually bubble and blow out easier in my opinion. Judging by the tire and profile I see you are driving a m850. If you want a more permanent solution switch to 245/40-20 fronts and 275/35-20 rears. I did as well as few other forum members. You get more sidewall which makes all the difference in the world. In addition to helping protect you from situations like this you will also notice when you hit road imperfections it's less jarring. Another plus is the tire fills the wheel well better.

While I basically agree with these statements, I would however add that general tire fitment guidelines recommend a rolling circumference difference of +/- 1.5-2.5%, 3% max, before adjustments to the speedometer, ABS & ESP systems are required/recommended. The tire size suggested here is a 4.2% change.

[Mgrae456]

Originally Posted by yugrac

While I basically agree with these statements, I would however add that general tire fitment guidelines recommend a rolling circumference difference of +/- 1.5-2.5%, 3% max, before adjustments to the speedometer, ABS & ESP systems are required/recommended. The tire size suggested here is a 4.2% change.

I'm sure you are right. I'm just going off the way my car drives which is much approved. The speedometer is also more accurate. If you look at the Alpina B8 with the same size wheel they run with the same larger tires I'm running. Maybe Alpina tunes the suspension a bit different but it does start it's life as a m850. The issue with the M850 is the extreme low profile of the tires. They are much lower in profile then an M8. It makes for a difficult experience if you live in an area with imperfect roads. You end up feeling every imperfection and damaging tires and rims like OP did. I'm in New York City I basically had no choice if I wanted to enjoy the car. By the way my BMW tech that I've known for 15 years gave the move his blessing. Which reminds me I was supposed to put him in touch with snowbimmer

[snowbimmer]

Hey Mgrae456, no worries. For now I kept the same profile tire, but went up in width with wider rims, so I now have a slightly taller tire. The new width also pushed the fronts out 7mm and the rears by 15mm, giving the car a more aggressive stance. The ride and, especially, the handling has been greatly improved. The rears ended up 1/2" taller, but the profile looks a lot beefier. I'm happy. (And, our potholes are spreading like a flesh eating fungus this spring)