I have a '17 JCW Clubman with '19s. I need new tires and was hoping to increase the sidewall in an attempt to cushion the ride a bit without downsizing the wheels. OEM dimensions are 235/35/19. Has anyone had luck with altering these dimensions on stock JCW '19 wheels? And by luck, I mean no rubbing or fitment issues. I'll put Pilot Sport All Season 4s on it when I change up but was curious what the options were if any.

 

I don't have first hand experience on a 2017 JCW Clubman, but you can usually gain a little bit of sidewall by upping the width by one step - 245/35-19. This doesn't add too much to the diameter, so you don't have to worry too much about speedometer error.

I like to use this site for clearance checks:
https://www.wheel-size.com/calc/

 

You can get 235/40/19's as that will give you more cushion. Worn be a clearance issue unless the car is slammed. Going too wide on the wheel (I assume it is an 8.5j?) Will look odd imo.

 

The stock width on the 2017 is 225, the 2020 JCW is 235. If your rim width is 8”, 235 would be the safest option. You’ll gain 7mm in diameter and only be off by -1%.

If you go 225 and increase to 40 profile, your speedometer will be -3.5% accurate
as a trade off for 22mm in diameter. It’s a lot but extra meat.

I have 19’s and 225, r35 on 7.5 width rims with Michelin a/s 3+. It’s more comfortable than my 18’s on continental runflats for winter.