I am planning to start doing some autocrossing with my Cooper in HS. I am going to use a 16X6.5 wheel and will probably go with a Falken Azenis tire to start out with. The RT215 tire is available in a 215/45/16 size, while the newer RT615 is available in 205/40/16. I looked up the specs form Falken's site. The RT215 in 215/45/16 is 23.5 in diameter and 8 in tread width. The RT615 in 205/40/16 is 22.5 in diameter and 7.2 in tread width. So here are my questions...



1. Would I be better off with the wider contact patch of the RT215, or the smaller diameter and shorter sidewall of the RT615?

2. Is the newer RT615 an improved compound, or just a different tread design?



Thanks for any guidance you guys can give me. I am new to this and looking to soak up as much advice as I can.



Thanks,

Brad

 

I can't objectively answer either of your questions. I can tell you that I have been running the RT-215 215/45 R16 Azenis on my 05 MCS w/LSD and the car has done very well with these tires mounted. I have not driven on the RT-615 but have been told by some very good STS drivers that they do not perform as well as the RT-215 unless you have them shaved to avoid tread squirm. This is primarily what I based my purchase on as I did not have enough cash to shave tires and to half tread depth and only get 50% life out of them. I also plan to use these as a track tire, so the minimal tread depth would have been worn down even quicker with the miles on the track.

I have driven on the RT-215 Azenis and the Kumho MX. I greatly prefer the firmer sidewall and better turn in of the Azenis over the softer side wall and better performance when hot of the MX. I have been told that the new Azenis doesn't quite have the turn in off the old RT-215 but isn't as soft as the MX. Hopefully I'll get to drive some RT-615's soon to judge for myself.

Joe

 

Brad,

I run both tires. RT-215's mounted on 16" x-lites and RT-615's mounted on 16" NZO Monza wheels. The answer to you question is "it depends". I think depends on what kind of track you are running. The smaller 205/40/16 is much smaller diameter which changes your gearing. I use the smaller tires on "short tracks" running say under 40 seconds or courses with a lot of low speed manuvers. The gearing helps off the line and bottom-end acceleration (at least until my inside front wheel starts spinning). The bigger tracks, say 60-70 seconds, or tracks that are wide open, I would run the larger tires. You don't want to get 3rd gear and spend too much tiime shifting.

As far as the grip comparison, it is tough to compare. I have 2 different sizes and on different wheels. I feel the grip of the RT-215 is awsome and I wish they did not stop making them. It was a great tire. Buy as may as you can before they are gone. The RT-615's are very good also. I just wish they came in a larger 16" size that would fit the MINI.

IMO, I think the diameter issue is almost as important as the treadwith. Bottom line "Wider is Better". I am probably looking at buying 225/45/16 Hankooks Rs2 to replace my RT-215's when they finally go.

Mark

 

Mark & Joe,

Thanks for the input. I think I'll go for the RT215's for now, as they probably won't be around much longer. I can always get a set of the RT615's later on.