Maximum rim size I can put on my tyres?

[B135i-e82]

Hey guys!

Probably a real noob question and have looked on the threads but cant find much

Ive got a set of run flat tyres with the stock OEM style 261 rims, I like them but want to change up the look.
I think from memory the fronts tyres are 215/40 R18 and rim size is 18x7.5 (I THINK LOL)
Rear Tyres are 245/45 r18 and rim size I think again is 18x8

Whats the max rim size I can put on these tyres?
I think 18x8 on the front should be alright but the rears Im more worried about as most rims these days are 18x9.5 on the rears.
And if I go bigger rim size I don't think I will have the issue of rubbing?

Thanks so much guys

[Simonnn]

The stock 261Ms are 18x7.5 on the front and 18x8.5 on the rear.

Stock runflats are 215 fronts and 245 rears as you have stated, However I have had 225 up front and 255 on the rear with no issues at all on these rims.

I have had 18x8 +38 and 18x9 +38 with the 245/215 combination with no issues either (rear guards need to be rolled if you plan on lowering the car).

I currently have the standard VMR/GTC fitment of 18x8.5 +45 fronts and 18x9.5 +50 rears with the 215/245 combination which I find is a bit too skinny.

Hope this gives you a rough idea of fitment on these cars!

[vtl]

Personally I think you would get more enjoyment out of the car by replacing the runflats with normal tyres. Ride quality, grip, and probably wear are all going to be better vs the runflats.

I would also imagine run flats wouldn't work well on a stretched fitment because of the solid sidewalls?

[B135i-e82]

Originally Posted by Simonnn

The stock 261Ms are 18x7.5 on the front and 18x8.5 on the rear.

Stock runflats are 215 fronts and 245 rears as you have stated, However I have had 225 up front and 255 on the rear with no issues at all on these rims.

I have had 18x8 +38 and 18x9 +38 with the 245/215 combination with no issues either (rear guards need to be rolled if you plan on lowering the car).

I currently have the standard VMR/GTC fitment of 18x8.5 +45 fronts and 18x9.5 +50 rears with the 215/245 combination which I find is a bit too skinny.

Hope this gives you a rough idea of fitment on these cars!

That gives me a real good idea, thanks so much!
I don't think I want to lower the car anymore, I'm pretty happy with the m sport suspensions ride height, might be to high for everything one else but Im the type to be yellow stickered due to every other car ive had lol

[B135i-e82]

Originally Posted by vtl

Personally I think you would get more enjoyment out of the car by replacing the runflats with normal tyres. Ride quality, grip, and probably wear are all going to be better vs the runflats.

I would also imagine run flats wouldn't work well on a stretched fitment because of the solid sidewalls?

Yeah the run flats aren't that great haha but id rather keep them for now until they pop then get some normal tyres

[dh58]

I ran 225/255 but not on run flats and was extremely happy with it. No issues at all.

[froop]

I think as long as your offsets are fine you're probably ok to fit any reasonable width wheel with those width tyres. The most common wider width is 18 x 8.5 front and 18 x 9.5 rear with the right offset. With stretching you could probably go wider and poke the rim but as vtl said, I'm not too sure whether stretching RFTs will work. You're best to ask a tyre shop with experience fitting RFTs whether they can be stretched or not.

[Simonnn]

I've had a minor stretch of the stock RE050 RFT 215/245 combination on my 18x8 and 18x9 +38 set, no issues at all (was a bit of a harsh ride though!)

[B135i-e82]

Originally Posted by froop

I think as long as your offsets are fine you're probably ok to fit any reasonable width wheel with those width tyres. The most common wider width is 18 x 8.5 front and 18 x 9.5 rear with the right offset. With stretching you could probably go wider and poke the rim but as vtl said, I'm not too sure whether stretching RFTs will work. You're best to ask a tyre shop with experience fitting RFTs whether they can be stretched or not.

yeah that's true, might have to check if I can stretch the run flats or not.
Want to go 18x9.5 on the rear but that's IF it can be done haha if I cant then I will have to go 18x8 or 8.5
Thanks for your help and advice!

[froop]

Originally Posted by B135i-e82

yeah that's true, might have to check if I can stretch the run flats or not.
Want to go 18x9.5 on the rear but that's IF it can be done haha if I cant then I will have to go 18x8 or 8.5
Thanks for your help and advice!

Chances are you will be able to go up to a maximum of 8.5 on the front and 9.5 on the rear with your current tyres but best to check for safety.

According to tirerack, http://www.tirerack.com/tires/tires....nza+RE050A+RFT, you can do it but still better to check with your local dealer.

[B135i-e82]

Originally Posted by froop

Chances are you will be able to go up to a maximum of 8.5 on the front and 9.5 on the rear with your current tyres but best to check for safety.

According to tirerack, http://www.tirerack.com/tires/tires....nza+RE050A+RFT, you can do it but still better to check with your local dealer.

Thanks so much for your help Froop, didn't know about that website.
I'll definitely still go check before purchasing, Will post photos once I get it done

[135]

Originally Posted by B135i-e82

Thanks so much for your help Froop, didn't know about that website.
I'll definitely still go check before purchasing, Will post photos once I get it done

There is a difference between the wheel width (as stamped on the wheel) and the actual/total wheel width measurement. The former is measured from the inside of each flange where the wheel and tyre make contact, while the latter includes the flanges and is measured from one outside edge to the other. The flange on either side measure very close to 1". Therefore, the total width of the OE 7.5" front and 8.5" rear wheels are, for all intents and purposes, 8.5" and 9.5", respectively. As you can see, the OE run-flats with a section width of 8.8" and 9.8" are a nice match to the total width of the OE wheels, being slightly oversized by 0.3", which is 0.15"/~4mm overhang on both the inside and outside of the wheel.

The "Measured Rim" for the 215 OE tyre is 7.5" while for the OE 245 tyre it is 8.5". It is generally accepted that if a tyre is fitted to a wheel larger than the Measured Rim then 0.2" will need to be added to the tyre's sectional width for each 0.5" increase in wheel width, as stamped on the wheel.

Now consider using 8" front and 9" rear wheels, as stamped by the manufacturer, which are actually 9" and 10", respectively, total wheel width including flanges. If you were to fit those same run-flat tyres on, the tyres' section width increases by 0.2" to 9.0" and 10.0", which are now a perfect match to the new wheels.

Being run-flat tyres, the sidewall is much stiffer and , therefore, less amenable to being stretched, so it's probably wiser to use wheels that are the same width as, or perhaps 0.5" wider than, the OE wheel.