F: 265/35/20 R: 305/30/20 on 650i GC??

[siliconvalleyf06]

Hi all, I have searched and searched different articles on 20" rims with different tire sizes and offsets, but I haven't found anyone who has accomplished this combo.

I am buying new rims and tires and want to know what kind of offsets I should get to make the following tires work?

I am thinking F: 20x9 with either 265/35/20 or 275/35/20 and R: 20x10.5 with 305/30/20 or 315/30/20 if possible.

Thoughts?

(Sorry if these sizes have been discussed before)

[upstate650]

X drive car or no? Those sizes may work if it doesn't have x drive but will depend on offsets. If you have x drive you need to keep diameter of tires the same. 255/35/20 and 295/30/20 is ideal for x drive. Use 9" wheel in front, 10" in rear for x drive.

[siliconvalleyf06]

Good point Upstate650. Mine is rwd.

I'm hoping someone may know what the offsets should be to make the tires fit.

[Walt White Coupe]

I think keeping the tires the same overall diameter is not just an XDrive issue. The "stability control" systems also require the proper tire sizes to function properly.

[upstate650]

Originally Posted by Walt White Coupe

I think keeping the tires the same overall diameter is not just an XDrive issue. The "stability control" systems also require the proper tire sizes to function properly.

wrong. M vehicles come with different diameter tires.

[upstate650]

Originally Posted by siliconvalleyf06

Good point Upstate650. Mine is rwd.

I'm hoping someone may know what the offsets should be to make the tires fit.

offset is how far the wheel extends from the hub, not a width issue. A 265 tire will fit on a 9" wheel. 275 is a lot of width, would be better with a 9.5". 315 would definitely require 10.5" wheel, and 305 would be better served there as well unless you like the bulged look. 295 fits perfect on a 10" wheel. The issue you will have with wider wheels is you won't be able to utilize a concave wheel that looks so amazing. There aren't a lot of people running odd sizes on these cars, so it may be hit and miss to find what works and doesn't rub. Based on my personal experience, the offsets of the M5 343 wheel are the absolute maximum in the rear. You could probably run 5 more mm of poke in the front than the M5 343, but that is with my tire sizes. If you run a wider tire the bulge will extend a touch further.

When looking up the 343 offsets, make sure you use M5, not M6 numbers, as the M6 wont fit on regular 6 series. Use an offset calculator to compare what you want to do to a known quantity like the M5 343 wheels.

[Walt White Coupe]

wrong. M vehicles come with different diameter tires.

The stability control systems depend on the car having the same size tire or if it came with a different diameter tires front and rear that you maintain that same ratio of diameters as originally installed.

[upstate650]

Originally Posted by Walt White Coupe

I think keeping the tires the same overall diameter is not just an XDrive issue. The "stability control" systems also require the proper tire sizes to function properly.

Originally Posted by Walt White Coupe

wrong. M vehicles come with different diameter tires.

The stability control systems depend on the car having the same size tire or if it came with a different diameter tires front and rear that you maintain that same ratio of diameters as originally installed.

your second statement is different than your first. Yes, you generally want to keep the ratios the same, but it isn't critical to stability control operation like it is for x drive and your transmission. Stability control is reacting to the motion, traction, steering input and slippage of the vehicle, not measuring rotation. What he is talking about doing is a mild change in diameter and the ratios between diameter.

[siliconvalleyf06]

I appreciate the replies. I think I did a poor job of asking my real question.

The question is: What offset do I need to be able to fit the following wheels/Tires package on my 2016 650i GC RWD (No EDC)?

Front:
Rim: 20x9.5
Tire: either 265/35/20 or 275/30/20

Rear:
Rim: 20x10.5 or 20x11
Tire: either 305/30/20 or 315/25/20

[upstate650]

See my earlier post. I think I covered it. But beware because you will be pushing the limits and could encounter rubbing.