should I slap 245/45/17 toyo R1Rs on mai C-Street car?

[7thgear]

Originally Posted by jdrxb9

- look forward to your findings!

I do as well




the events that I run always put me into the questionable RPM range when exiting corners and never did I hit the rev limiter of 2nd.

The very few times I had to grab 3rd, it wasn't for very long, so almost like a wasted shift.

So I hope with the very slight change i'll have a stronger 2nd gear all around and a slightly more usable 3rd.




So my choice is driven solely by the events that I run.

[renfield90]

Originally Posted by jdrxb9

Anyone gone any further than a thought experiment on the 225/45-16?

Apparently they've been available for a while, but I just noticed Dunlop is offering the ZII Star Spec in this size and its the first 16" I've seen that might be worth testing for CS: vs the 235/40-17 its only 0.2" narrower (by spec), but gives a 2% gearing advantage and lowers the whole car by 1/4"

Yes, you'll run of out 2nd gear sooner (~56.7 vs ~57.8), but if you want to do well on a local/small lot or think you'll be shifting to 3rd anyway... Plus, they are cheap and I have some almost-CS-legal 16" winter alloys I could repurpose for testing...

It's not a bad idea for a small lot, but that's where the benefit ends. If you're on a lot big enough to allow for third gear speeds, you run the risk that sections where you may have briefly touched the limiter on normal tires now become awkward "do I shift or stay on the limiter a long time" sections.

I guess if you knew for sure that the course would favor a 16" tire and not hurt it, then it would make sense, but the point of this sport is you don't know that.

Regardless of which tire you pick, there is a course out there that makes your final drive annoying. As a result I tend to not worry too much about tire diameter unless I'm going significantly different than OEM.