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I don't have time data for the compare but I can compare. Car is a 1720 lb Lotus Europa with a Toyota 2GR 3.5 V6 turbo easily 450hp. 15x8f w/205, 15x9r w/245.
I ran the Rival-S for 23 SCCA AutoX events starting in 2019. They were old but still had plenty of tread life. A month ago I switched the Nankang CR-1's. On the street the Rivals always hooked in second, always and usually in first. The CR-1's never hook in second. This is not power shifting, just roll on and spin and enjoy the rear drift. I was more than concerned. On autoX launches, it is a hard to launch car. Get it in second and it's good. I just did an Auto X on a road coarse with the Porsche Club. Same auto x style with cone slaloms to try to keep speed down on the straights and one run, come in. First run. Launch on the CR-1's is the same in first, easy to over power, go to second and the rear drifts like it has never done ever. easy to catch but wtf?. Second run they hooked after getting warm. Third run and they were done with heat. I can't compare them to the Rival's here because I have never done this track with them but I have many launches and second gear WOT on straights on the street and coarse. If you have torque, they are not the tire. I don't know what these tires would be good for. I left boost down to 6 psi from my normal 8 psi. Yesterday, every 2nd gear wot (4) was a light spin and drift. Wifey even said why is it spinning so much?
I'm stuck with ordering more Rivals. Trying a cheaper RT660 that many heavier V8 CAM guys seem to like or a narrow 225/50-15 A052. If any other AutoX guys on here run the RT660's or A052, I would love to hear how they are cold.
That would be ideal but I built it when the 245 Rival-S just came out and was the widest at the time. The flares will not allow wider. It has a 38/62% f/r so it hooks up better than most for the lb/hp.
I would go with the A052's which is one of the best. With that said I run the Rivals 1.5 S and they might be the second best. There is also the RE71RS if available your sizes.
I looked into the A052 but the 225/50-15 is their widest in 15 and taller but I don't mind the height. A052 has an 8" tread, BFG is 8.5", I think the RT660 is 8.8". I'm afraid with less footprint I will get them too hot after run 2 and they aren't cheap to just try out. RE71RS is the same size as A052. I just got two RT660's delivered today and will mount them tomorrow and see if they have any longitudinal grip. Side by side, durometer on Nankang is 80 (after one event day plus 100 miles street), RT660 is 83-84. When I got the Nankangs's they were harder on the durometer than 4 year old BFG's with over 100 runs. I'll update in a few days.
4yro Rivals are not a going to give you a good understanding of their capability.
It's funny, They are dated 2017. It took 2 years to get the car finished after purchase and on a track in 2019. I ran them 4 season and drove the car just before putting the Nankangs on. I've run RA1's, you cord them before they get hard. V700's became hard way before wear bars. Some tires have magic in their rubber, I think the BFG's might be one of them.
Some logged data with RaceLogicTC between the CR-1 and RT660 from today. On the RT660, the air temp 48f, the CR1 was 76f I checked date time against local weather. Both logs looked similar in time being driven and number of second gear accels before the screen shot so that is the same. The road temp on the RT's is much cooler. Boost is the same. It's not a fair compare with the temps. I'll log again when it's warmer out and see how much better the RT660 is. Unfortunately all the logs I have on the BFG are on the old no more laptop. I have another autox and then the followimng day a track/autox in a month. Same track I ran the CR-1's at.
12-11-2022, 12:20 PM
Rival-S vs Nankang CR-1
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