X5 30d

MrSweet1991 · 08-04-2022, 06:29 AM

Hi All,

Sorting many many issues with the car at the moment but when I was starting to work on the electronic parking brake actuator the inside wall is down to threads on the rears. So I looked for some tyres but the expected combinations don't match what I have.

The front tyres are "Rotalla Setula s-race ru01" Size 255/45zR20 105y
The Rears are "Rotalla Setula S Race RS01+" Size 275/40zR20 106w

Alloys are Fox FX3

wcs531 · 08-05-2022, 02:49 PM

The rolling diameters of your tires match factory specs kind of.... The fronts match non sport spec and the rears match sport spec, so they have a 1% discrepancy between front (29.0") /rear (28.7") which is at the upper end that BMW recommends.

The only things that really matter are:
1. Rolling diameter within 1% at all four corners
2. The tires dont rub (Really only an issue in front with oversized tires - there are other threads that address this)
3. The tires fit on your rims - this one is somewhat relevant cause if all your rims are 20x9.5 the sidewall profile will look different (and in some cases tires wont fit at all).

Factory is 255/50/19 all around non sport or 275/40/20 front 315/35/20 rear for sport rims, so you have something in between which is fine.

This site is good for looking at rolling diameters: https://tiresize.com/calculator/

If all your rims are 20x9.5 you could just go square all the way around 255/45/20 (can play with sizing a bit but i think 255/45/20 is the narrowest you can go on 9.5" rim.)

Staggered 255/45/20 front and 285/40/20 rear are same rolling diameter which could work, just might look funny on square rims.

08-04-2022, 06:29 AM	#1
MrSweet1991 Captain 129 Rep 828 Posts Drives: BMW E90 330D M Sport Join Date: Apr 2017 Location: West Midlands iTrader: (0)	X5 30d - Strange Staggered Setup? Hi All, Sorting many many issues with the car at the moment but when I was starting to work on the electronic parking brake actuator the inside wall is down to threads on the rears. So I looked for some tyres but the expected combinations don't match what I have. The front tyres are "Rotalla Setula s-race ru01" Size 255/45zR20 105y The Rears are "Rotalla Setula S Race RS01+" Size 275/40zR20 106w Alloys are Fox FX3
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08-05-2022, 02:49 PM	#2
wcs531 Second Lieutenant 97 Rep 281 Posts Drives: E90 335xi / E70 X5d Join Date: Jul 2014 Location: Philadelphia iTrader: (1)	The rolling diameters of your tires match factory specs kind of.... The fronts match non sport spec and the rears match sport spec, so they have a 1% discrepancy between front (29.0") /rear (28.7") which is at the upper end that BMW recommends. The only things that really matter are: 1. Rolling diameter within 1% at all four corners 2. The tires dont rub (Really only an issue in front with oversized tires - there are other threads that address this) 3. The tires fit on your rims - this one is somewhat relevant cause if all your rims are 20x9.5 the sidewall profile will look different (and in some cases tires wont fit at all). Factory is 255/50/19 all around non sport or 275/40/20 front 315/35/20 rear for sport rims, so you have something in between which is fine. This site is good for looking at rolling diameters: https://tiresize.com/calculator/ If all your rims are 20x9.5 you could just go square all the way around 255/45/20 (can play with sizing a bit but i think 255/45/20 is the narrowest you can go on 9.5" rim.) Staggered 255/45/20 front and 285/40/20 rear are same rolling diameter which could work, just might look funny on square rims.
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