Hey all, I've been looking at different setups and I've always like the meatier look of larger tires. My 2017 F54 Clubman comes stock with 225/45R17s. I recent got a set of Rotiform BLQs in 18x8.5 et45. I would typically pair a set of 235/40R18s on these. However, would it be safe, assuming zero clearance issues, to stick with the 45 ratio sidewall and putting on a set of 235/45R18s to give it that meatier look. This goes outside of the general 3% rule and puts it around a 5% increase in size. Outside of the speedometer reading incorrectly, will this create any serious issues?

TLDR, will going from a 225/45R17 to a 235/45R18 create any big issues?

Thanks in advance

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If you are still at stock ride height, you’ll probably be fine...

Measure the clearance around your stock wheels, then go here and compare:
https://www.wheel-size.com/calc/

 

Thanks for the website, I've actually have never seen that one with the wheel well dimensions.

For further clarification, I'm more concerned with the larger size throwing an engine light or my car going into limp mode. Are the BMW Minis that finicky?

 

Just make sure all four wheels are the same size

 

this. most awd set ups are very dependent on all 4 tires having the same height.

 

All wheel drive is designed to have each tire diameter to be equal or within a few % difference. However there can be staggered tire sizes if you use different wheel widths, just make the overall tire diameter the same front vs rear.

As tires wear down the tire diameter gets smaller but only a little, it's important to keep tread depth relative close front to rear as wear may be greater on either front or rear axle, usually fronts will wear down faster.

The other thing is if you have a flat tire and need to replace a tire you can't just add a tire if the others are worn down, either change to new tires on an axle or replace all four tires at once which can be expensive.

And if you replace a tire or two you need to match the exact tire model for best results, otherwise the tire compound, tread design or tread pattern may be mismatched and not work that well. Therefore always try to match the new tire to the old as needed an exact replacement.

 

I have no idea if 235/45 R18 will cause clearance issues, since I have zero experience with the current F54 Clubman, but even 235/40 R18 is already taller than the factory option 225/40 R18 and more so than your stock 225/45 R17 tires. Overall dia directly affects gearing, so gearing will be noticeably taller with 235/45 R18, resulting in slower acceleration. I'm sure your new Rotiform wheels along with 235/40 R18 tires will look great.