15" vs. 16" - Track use

[Old_skool_bmw]

Question is with regards to track day tires/rims.

I have been pondering whether to buy a set of 16" rims or use the 15" rims I already own.

I am wondering if I will see any major benefits of a 16" rims vs. a 15" rim. Obviously with 16" I can opt for a tire with shorter sidewall but I have never used 15" for track day stuff and am wondering if the improvements are 'marginal' or if there is significant difference between the two Sizes??

Thinking of 215/50/15 on 15" x 7"
Not too sure on 16" tire size yet.


Laurence

[Markus]

why not the original 7,5x16 with some 225/45/16 Semi Slicks?


Markus

[UweM3]

why not the original 7,5x16 with some 225/45/16 Semi Slicks?


Markus

second that. 225/45/16 is a very good size for the M3 IMHO

[temple]

Depending on the track, 225/45- 15 work best at Infineon, Thunderhill, and Laguna Seca, especially if you are running near stock hp.
And the side wall are plenty stiff, especially if you are running Hoosier R6 or A6.

[robertm]

First assume you can get the overall dia the same regardless of the wheel. If not then you will lose some gearing advantage with whichever one is larger dia. Second, lets assume the weight is equal. Assuming that you will most likely have a greater centrifical force with the 16" wheel. This will effect acceleration and braking slightly. The 16" wheel should give you slighly better brake cooling. There is just more space between the pads and the wheel. (typically, really depends on the wheel).

Forgetting all that for a moment, the wheel which give you the most tire contact patch is the one you want. Up to you to figure out how you want to go about that.

There really isn't hardly any advantage to going to a larger wheel unless you are cramming larger brakes under there or you have some other justification (like a deal on tires or somn.) If it where me, I'd get a set of lightweight 15/8 wheels and put 225/45/15 tires one there or as wide as you can get with your setup. This wil give you best bang for your buck and guys with e30m3s have been doing this exact setup for 20+ years now ;-)

[Old_skool_bmw]

Thanks for the tips guys..
M3 had 15" x 7" before I put the BBS RS wheels on it so I think I will stick with the 15" and run the set-up of 225/45/15.

Also considering taking the track tyres off the BBS RS 17" I have as they are heavy and I really don't want to F**K them up on the track. (also cleaning them after would be a nightmare)

Will post back up when I have sorted a set-up


Laurence

[OLLIE_NZ]

You'd be pushing it to get a 225 on a 7 inch rim wouldn't you mate?

[temple]

I ran 225/45-15 R888 for a long time on stock rims and they worked great. Hoosier R6 will not work because of the width, so I went to tire racks 15x8 which are excellent for the price weight and money.

[fast325it]

I see 225/50/15 on stock rims all the time.

Do a search for Mick's posts. He's discussed this several times and runs only 15" wheels.

[Chris F.]

Is 225.45.16 as common as the 15" sizes mentioned? I haven't bought tires in a long time for my 16x7.5 wheels, but there weren't many options. I think I have Bridgestone S-03's, which I'm guessing aren't even made any more.

FWIW, I now run 225.45.15 Nitto NT-01 on 15x8 Tire Rack wheels on my e30 325is track car and have been very happy with that setup. They're shorted, but it works well with my 3.73 rear. On the M3, I always used 225.50.15 and it worked well on the tracks I ran w/ the 4.10.

On the M3, for autocrossing in particular, I felt a big advantage going from a lighter (<10lbs) 15x7 wheel to a heavier (~13-14?) 15x8 Kosei K1. I could drop a few PSI and not have the tires roll over. On the track...I'm not good enough to say what the difference was.

[lucid]

There aren't a whole lot of r-compound tire options for 16" wheels in the US (assuming you want to keep rolling diameter under check). Might be different elsewhere. I am running 225/50/15 cup tires on TRM wheels, mainly because the tires were on sale for $125. Otherwise, I would have gone for 225/50/15 BFG R1 slicks as they should offer more contact patch, and are a little cheaper than Hoosier--I hear they are pretty close to Hoosiers on performance. BFGs might be my next set. Has anyone tried them in 225/50/15?

[scaraveos]

why not the original 7,5x16 with some 225/45/16 Semi Slicks?


Markus

Markus, where from do you buy these tires? They have been discontinued before 3-4 years(at least in Greece).

[Markus]

a friend of mine sells them

Markus