[Burnt C6]

I'm not happy with the selection on tire choices for our 6M50i. We have 21" wheels currently with Run flats . I'm wanting to go to a 22" but have been told that the tire size difference will throw off things. I have a couple of questions I'm hoping someone can answer.

1. Can things be reset for the size change. I'm basically going to go with the non Run flat size tire option the BMW offers.
2. If no reset can be made will the fact the at factory sizes 65 MPH will be 64.2 MPH with the new sizes cause any real issues with sensors?



I'm wanting to put these wheels on. 22x10.5 front 22x11 rear. Tires will be 275-35-22 front 315-30-22 rear.
I was thinking of maybe going with a 325-35-22 but that rear tire would be 65 MPH vs 67.8 MPH new. That will make the miles on the vehicle incorrect if it can't be reset. current 679.54 rotations mile vs 651.45 new.

I saw a post from Ninefourteener about putting 35/25/22 on his with no real issues

thoughts?

[Ninefourteener]

I "believe" the setting in Idrive really just adjusts the top speed limiter for summer/winter tires. I don't believe it adjusts the speedometer settings.

Because.... 20, 21, and 22 wheel/tire packages, are all the same overall diameter. 20 wheels have taller tires, and 22 wheels have lower profile tires. Overall diameter is the same though, or negligable.

Yes, I went with a 335/25/22 on the rear, and a 295/30/22 on the front. Yes, my speedometer reads about 2mph slower than what I'm actually travelling.... because my overall diameter is slightly smaller. Not a huge deal to me, but you should be aware of it.

"Optimally", the overall diameter of the front wheels/tires and rear wheels/tires should be the same. A slight difference (2%, 3%) isn't a huge deal, as our cars are rear-based and designed to "slip" (which is why you can do rear-wheel donuts in our cars). In this instance, the rears can and do spin faster than the front. That means, any difference in overall diameter (2-3%) should reflect in a "slightly" taller front tire. Never a slightly taller rear. The shorter the diameter, the faster the wheel will turn.... and you want the front tires travelling slower than the rears as BMW intended, not vice versa.

Again, we're talking about the difference of a few millimeters. The equivalent of running low tire pressure on one axle. Minimal differences aren't going to cause catastrophic transmission failure. If that were the case, spare tires wouldn't even be feasible. Our cars are DESIGNED to slip.

Admittedly, a 285/30/22 would have been a "more perfect" match to the overall diameter of the rear wheels, but there were no companies that made both sizes, so I opted for a 295/30.

When you go as wide as I did on the rear (335 on a 12" wide wheel), there are no "taller" options. 335/30 would be great, but 335/25 was all that was available.

Another option is to go with a similarly width-sized wheel, but with a more aggressive offset, to give the "appearance" of a wider stance. That way, you can use stock-sized tires, and not worry about the speedo issue.

Theres a great website.... "willtheyfit.com"... or something like that..... that will help you choose appropriate tire sizes.

Again, the #1 consideration isn't necessarily the size.... but rather that the fronts and backs have "as close to equal" overall diameters. The X5M uses 22s in the back, and 21s in the front, but the overall diameter is the same.

Hope this helps.

[PREDATOR 007]

Thanks Nine, that was very informative.

[Burnt C6]

Thanks for all that information. I saw your post on the wheels and other things you have done. Your X looks fantastic. I will check with my buddy that sells the Feraada wheels about what offset are available. also will get on the web line you posted to see exactly what I will need. I will also get on discount tire's web site as they have a tire size comparison page to make sure I'm as close as possible on the sizes.

[Ninefourteener]

No problem. I actually spent months researching this. Here's some issues you'll run into;

1. Use "will they fit" to determine the difference between the overall diameter of the front & rear tires. May sure you have as "close to perfectly equal as possible. No more than .4" max height difference.

2. If there is any difference at all, no matter how small, fronts should be the taller one.

3. The 2 tires you picked - do they even exist?

4. The 2 tires you picked - if they exist, can you get all 4 in the same brand/model?

5. Are they decent tires, or Chinese Garbage?