[awt]

I've stumbled across (another) set of OEM style 310 wheels, which is 8,5x20 and 10x20 as you may know.

My plan is to use these with winter tires, but winter tires with the star symbol in the OEM sizes doesn't exist (at least not without robbing a bank), so I have to figure out something else.

I'm on the lookout for two more front wheels, so the I could run square setup all the way, but I can only find rear rims for sale, so I need a backup plan.

Using 245/40-20 and 275/35-20 without the star symbol is not on the table, and 245/40-20 on all four is to much tire stretch on the rears.

I was thinking about 255/40-20 on all fours maybe could work? Any other suggestions?

[Tjalle]

installing tyres on rims, which they are not designed for is not a very good idea. You will have less performance and wear.

If you can find Conti, Michelin or Hakka in right size, I would recommend that.

The star means BMW test engineers have driven them and approved use - that does not mean all other tyres are crap or dangerous.

I see your point - I have 310M:s on summertyres, but I accept less look on winters with 18" AEZ Yacht with Conti studded tyres. 18" - studded or non-studded- is a far more better size for winter - both in Norway and Sweden

[awt]

255/40-20 is legal on both 8,5" and 10", but it will be some "balloon" at the frond and some stretch at the rear.

You're wrong about the star symbol by the way.

Tires with the star symbol have the same rolling diameter front and rear, even with dimensions that shouldn't match completely.

245/40-20 and 275/35-20 have a rolling diameter difference of 0.5% according to calculators, but with the star symbol the difference is 0%. Same story with the 5-series (245/40-19 and 275/35-19), 1% difference according to calculators, but 0% difference with star symbol. In other words, tires with star symbol is a little bit bigger (or smaller) than the dimension should be compared to non-star tires.

Because of this, you should always use tires with star symbol when running staggered setup on cars with xDrive, as the transfer case can be broken if not. You will also risk the guarantee (two years left on mine) when running staggered wheels without the star symbol.

My problem is that there isn't winter tires with star symbol in these dimensions, so I have to look at other options.

I have 17" studded in winter now (I really don't like studs), and 19" and 20" in the summer. Plus the extra set with 20" I bought today. All OEM.

I had 19" non-studded winter tires on my e61 for three years without any issues, so I don't see a problem running 20"s, apart from the availability.

[335iAP]

It'll be fine if you don't mind the look. I wouldn't like the visual contrast in stretch but it'll be fine.