[Gypsyking]

I have a 2018 330i xDrive with 33,000 miles on the clock. The car still has 5/32nd tread depth on the Bridgestone Potenza S001 RFTs. This is not my daily driver. For winter I have a dedicated set of winter tire/wheel combo.

The setup is stock on 19-inch 403M wheels.

Front: 225/40ZR19 (8JX19 ET36)
Rear: 255/35ZR19 (8.5JX19 ET47)

I want to transition to non-RFTs once these tires hit the 4/32nd tread depth with a revised setup as follows:

Front: 225/45R19 (+3.4% OD)
Rear: 255/40R19 (+3.8% OD)

The overall rolling diameter difference between the front & rear with the increased profile remains zero.

Now, I realize that the increase in overall rolling diameter from the OE tires should be within 3% however I don't see any other way to increase the sidewall thickness. I want to stick to stock wheels. Please advise. Thanks.

[hooligan_G01]

It shouldn't be an issue, other than your speedo will read a little slower than it previously did. Depending on your car, that could be a good thing.

[alohasurftoad]

The vehicle height will rise 13mm. Also, the 3.8% "heightened" gearing and increased tire weight moment will slow tip in acceleration on paper, although I'm not sure your butt dyno will notice.

[jmanB45]

That is a serious increase in diameter (27"). For context, here is 245/45/18 which is 26.7"

https://f30.bimmerpost.com/forums/sh...0&postcount=10

[Ennoch]

Originally Posted by hooligan_G01

It shouldn't be an issue, other than your speedo will read a little slower than it previously did. Depending on your car, that could be a good thing.

The speedo will likely to be 1-2mph under reading at 70mph and you'll possibly get some rub on the front. I run 245/45/18 winters and it's paper sliver clearance at full lock on the front, and the speedo went from an actual 68.5mph at 70mph to absolutely bang on.

[hooligan_G01]

Originally Posted by Ennoch

The speedo will likely to be 1-2mph under reading at 70mph and you'll possibly get some rub on the front. I run 245/45/18 winters and it's paper sliver clearance at full lock on the front, and the speedo went from an actual 68.5mph at 70mph to absolutely bang on.

Stock height?

245/45/18 is 26.7", 225/45/19 is 27" - if you're driving a stock height xDrive car and the clearance is that tight with your tire size, the OP is definitely going to have some clearance issues.

[Gypsyking]

Gents,

Thank you all very much for chiming in with your valuable insight/suggestions. For the winter tire/wheel combo I have invested in an aftermarket 18X8J ET 35 alloy wheelset. I run Continental Viking Contact 7 225/45R18 tires and am very happy with the setup.

I have decided to stick to the stock size for the summer and will order the non-RFTs in May next year. I'm gravitating towards the Continental ExtremeContact DWS06 PLUS however the heart says Michelin Pilot Sport 4 S.

Please note that we have a long winter from November to April with peak temperatures touching -31F therefore there is a shoulder season (October & May) where the temperatures can drop to 30F or even lower. Considering all of that it makes sense to have a good All Season UHP tire (DWS 06 Plus) rather than out and out UUHP tire (Michelin).

Thoughts?

[jmanB45]

The Continentals are a solid choice and they ride great too, if that's what you wanted with bigger sidewalls. I have them and no complaints.

Can't go wrong with Michelins either, but you'll have to keep the winters on during the shoulder months.