From the link:

The outer shoulder portion has increased block rigidity, which has improved the cornering performance when cornering. According to the company's tests, the lap time was reduced by 2%, the average dry lap time was reduced by 1.1%, and the wear life was improved by 5% compared to RE-71R.

Looks like we have some first hand experience on the new RT660 tires from Falken. GRM's April publication has a comparison to the RE-71 and 615k. Thanks to @AndyHollis for the article.

The maxxis rc1s are apparently offered in 245/15... dont recall if I saw them mentioned

https://www.maxxis.com/catalog/tire-450-107-victra-rc-1

looking forward to reading that. Falken has added the RT 660 to their webpage. The great news is the size chart shows it coming in 205, 225, and 245 for 15" wheels.

https://www.falkentire.com/tires/pas...nis-rt660-tire

245/40R15 now an industry standard size. Cool.

If anyone is looking for RS-RR's right now, here is the cheapest I've seen them in a 225 @ $363/4. Just ordered a set for the beater since I'll run it in a 200TW class this year:

https://www.ebay.com/itm/4-Federal-5...005.m1851#rwid

Tempting to get a set for drive around tires. My star specs are about wore out.

Scratch that, seller claimed they were the last set and were old and refunded my money. Tried another seller for $380. If that flops too, I'm just ordering the dang VR-1's S2 compounds straight from Maxxis.

Surprising to me I finally went from 205 Toyo Prox to 225 Toyo R888R and the rain traction was mind blowing. I went from spinning in 2nd in dry to putting down 240hp all the way to redline in rain without spinning. When I ordered them at discount there was almost no other options in stock in the nation for 225.

Tire age and heat cycles can skew experiences sometimes, but it really sounds like a big improvement.