I've been researching for a while & still can't decide.

I'm running a 2008 MCS Convertible (R52) in G stock. BMW hasn't updated the topless models, so it's basically a R53 with a little extra weight.

That being said, since I have a little less torque than the R56s, I'm leaning towards 16" x 6.5" Roto Slipstream wheels with 215/40/16 V710's.

Wow, now that I've typed that, I feel much better. Almost like I've committed. I'm going to run the season that way & see what happens. If I see a deal on 2 used 17" tires, I can always throw them on my OEM rims (web spokes; light for a RFT rim) and try running 1 day with them on the front for comparison. Of course the weight will be greater than racing wheels, but anything we attempt will always end up being an apples to **** comparison anyway.

Any thoughts/comments/questions/criticisms?

 

The 16's are a good plan, plus they are much cheaper than the 17's and last longer.

 

Keith, I am curious why you think that the 16"s last longer. I found brutal tire wear, and a lot of that was from wheel spin. When I went to the larger tire, I decreased the wheel spin on the way out of a corner.

 

Kumho's last longer than hoosiers, They don't edge cord.

Modulation is your friend

 

With our practice event doused in rain, and our first points event rained out before G Stock could run, I *still* haven't been able to use my new 710s.

On the plus side, these things are going to last forever at this rate.

 

Fair enough. But this is more of a function of a tire model's availability compared to wear in a rim size, correct?I thought I saw that Kumho was coming out with a 215/40R17, to compete against Hoosier's 225/40R17.My issue with the 215/40R16 and the 205/45R16 is their height. They are both about an inch and change shorter than stock.

 

The empirical data says the 215/40/16 and 205/45/16 tires are faster on the R50/53 cars. It is still up in the air on the R56. (although the top 4 in GS last year were on 205/45/16's)

You will have less wheel spin on the taller tire, but is it worth the acceleration tradeoff.

 

I don't know if 225/45R17 has been tried, but I have a set of 225/45R17 Kumho V710s... would they rub on R56?

 

Finally got a chance to run the tires at the event yesterday. They fit fine, no rubbing (not that I expected any given the advice of everyone on the board). Gearing with the 215 16s is definitely an issue; the car was way up in the rev range through much of the course, and I might have benefitted from a shift to third in a couple of places. Other than that, though, I was pleased with the 710s overall.


I still have a lot to learn about how to drive a FWD car, but so far I am pleasantly surprised at the R56's willingness (eagerness?) to rotate.

 

I just tried out the same tires on my R56 too. My first time on r-compounds. The course was on the slow side with some really tight corners so I appreciated the slightly lower gearing (I know it may be an issue for some events, though it will probably even out).

One problem was major understeer - something I had dialed out when on street tires. With only 4 runs, I didn't get a chance to play with the pressures much though. Started 36 front 38 rear (cold), but the fronts were too soft and wearing past the shoulder. Quickly threw another 2psi in the fronts and that's where it stayed for the last 3 runs. I think I need to put at least another 2 pounds in the rear tires to get some rotation.

The other thing was I was breaking too early (not used to the extra stopping power of the V170) so I was entering some corners a lot slower than I needed too. It's like learning to drive all over again with these things - hopefully I'll get a better feel for them after the next event.

How did you like your setup, what pressures did you use?

 

just FYI, i run 225/40R17s, but i've also run 225/45R17s on my R56. I've even squeezed 245s on the car. 225s have *very* slight rubbing on the strut body, the 245s have much more, but don't do any damage.

d

 

Thanks. Rubbing on the strut body, so you are talking only in front? What was the wheel offest? I think stock has 48mm offset... I wonder how low we can go (maybe 42mm?) to avoid rubbing on strut body, but also on the fender.

 

it rubbed front and rear with the 245s. wheels were 42mm offset.

d

 

I'm using 235/40R17 R1s and they rub front and rear under cornering...but no real damage.

Per

 

Has anybody tried the 710's in 215/40/17 on R56? I was looking through tirerack website and saw them listed. Is this a new size?
I drove on Hoosier 17s last year and was debating what I was going to run on next year....

Thanks in advance,

yasu hane

 

Thats a new size, I would recommend trying it out on an R56. I will for sure if I don't sell my Mini.

 

I'm thinking about going back to an HS MINI (err..a clubman, actually) for the occasional local event when I'm not in the BMod car. So...If anyone wants to trade some Enkei 17x7s/Hoosiers for a 16" set-up, let me know.

Per