I have been researching this forum for several months. I am pretty much decided on the Rota Slipstreams based on weight, price, and durability. The difficult choice is size: 205/50/15 vs. 205/45/16.

- both are undersized by 4 to 5% (depending on the specific tire) for some added torque
- rim + tire weight bit less in 15", but sidewall flex less in 16"
- aesthetics favour 16" slightly, but not a big concern
- cost is somewhat ower for 15"
- good selection of rubber in both sizes
- the load rating for most 205/45/16 tires is lower than ideal, but the car is rarely (never) loaded with more than 400 pounds of people + stuff - should this be a big concern of not?

I will use these as my daily drivers in summer only. I don't autoX, nor do I intend to, but I may get back to doing some BMW driving schools at some point.

By the way, I'm replacing the R98's and runflats that came with my car 9000 km ago.

Rubber will probably be Bridgestone RE750 or SO-3 (wear rating of the latter a bit low for my purposes), maybe KDW2 (bit heavy), maybe Toyo (I have no experience with Toyo), maybe Dunlop Sport 9000 (no experience). Wet performance plus good wear are top priorities then stickiness in dry is #3.

Too bad the choice of rubber is so poor at 215 and that difficult to undersize diameter at 225.

Any advice? Thanks in advance.

 

"for some added torque"

You mean for increased mechanical advantage.

I think you have the right idea with what you are looking at.

I went with 205/50/16 and notice the difference.

I would be concerned with a 45 with the low sidewall. A little sidewall cushion isn't a bad thing on bumpy roads.

 

I have the Falken R215 (old version) 215-45x16 on stock x-lites and they work very well. A little smaller than stock, but no rubbing and lots of stiction.