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I currently have 18x11 with 315 Rival S tires. I think it can be generally accepted that under most circumstances the RE71R is a faster tire. Next season I need to buy new tires. I want to go faster, I don't care about any other factors. There are no RE71R to fit on my wheels. So I have 3 choices... All square setups.
1. Buy another set of 315/30R18 Rival S 25.5" tall tire 29#
2. Buy a set of wheels 18x10.5 and a 285/30R18 RE71R 24.8" tall tire 27# (There are some fast 4th gen running this setup today)
3. Buy a set of wheels 19x11 and a 305/30R19 RE71R 26.2" tall 31# (I have seen a couple 4th gen with this setup, never in person and never an AutoX)
Anyone with any experience please chime in, I can't decide.
I've been AX for many years in my TA. I think going skinnier would be a mistake, depending on how your courses or lots are. I'd take the Rivals (actually I just got 18x11s also and was hoping RE71Rs would be made in our size soon, been running 17x11s for a looong time). I personally think that 19" wheels would be too little sidewall. The only way that the 285s could possibly be any advantage over the 315 is maybe the course is pretty straight, with very low speed hairpins, no fast sweepers, no slaloms or so long as to make transitions easy and small cars have little advantage (like 100 foot slalom or something absurd).
I dont have any experience to know how much better the RE are over the Rivals. But the 30mm difference might negate it and make them about equal. Just guessing.
You could also get Hoosiers! They are good for ESP. But I guess you are in CAM.
I've been AX for many years in my TA. I think going skinnier would be a mistake, depending on how your courses or lots are. I'd take the Rivals (actually I just got 18x11s also and was hoping RE71Rs would be made in our size soon, been running 17x11s for a looong time). I personally think that 19" wheels would be too little sidewall. The only way that the 285s could possibly be any advantage over the 315 is maybe the course is pretty straight, with very low speed hairpins, no fast sweepers, no slaloms or so long as to make transitions easy and small cars have little advantage (like 100 foot slalom or something absurd).
I dont have any experience to know how much better the RE are over the Rivals. But the 30mm difference might negate it and make them about equal. Just guessing.
You could also get Hoosiers! They are good for ESP. But I guess you are in CAM.
Thanks Chris. I know it doesn't seem possible, but there seems to be a some info that the smaller RE71R are faster. I know of two people changed from 315 to 285 and think they are faster. And someone who ran back-back 305 RE71R to 335 Rival S and with two drivers the smaller tire was faster. And, yes my car is in CAM because it is modded out of reasonable classes. By the way the 19" sidewall is almost the same ~0.15" less. I'm more concerned about the front fitting, being they are taller. And they are heavier, the 285 is light and short which may be more nimble. With all that said, I likely will chicken out and stick with the 315, it seems the logical choice... but I want to go faster!
Ok so there was a sale so I bought some 285/30R18 RE71R. I don't have them mounted yet, but I thought I would share how big these are. The stack of tires was 47.5", so very close to 12" each (unmounted). Also I had concerns mounting on my 11" rim. But the distance between beads on these is 10 3/4". Super short tire unmounted as I got 24 1/4".
Anyone have a pic of a 285/30R18 on a vehicle? I'm curious if these are going to look dumb because of the small diameter... I may just mount a pair now since I'm impatient for spring.
@00PewterSS You get them mounted yet? I am in the same boat, although I have a new set of Forgestar 18x11 that I was planning on running another set of 315 Rivals. I have my older setup 18x10.5 that the 285 RE71R would work on.
These fit really well. Very little stretch maybe none. Tire overall is 12 1/8 old 315 were 12 1/2. Quit pleased. I measure height just under 25, so they are short.
Well, I wish I would have known that about a month ago! That ship has sailed now and for about $900 a set, that is a steal. I think these will work quite well given they are pretty oversize, a little lighter, short sidewall, and generally tires seem to work best on the widest rim.
Well, I wish I would have known that about a month ago! That ship has sailed now and for about $900 a set, that is a steal. I think these will work quite well given they are pretty oversize, a little lighter, short sidewall, and generally tires seem to work best on the widest rim.
ah right.
Yeah 315 RE71 would be nice to have on price difference alone. I don't have the experience to compare a RE71 to a Rival. I've only driven on the Rivals in the rain.
What do you think about lowering your gear ratio with that shorter 285? One course I ran this year bumped 67-6800 rpm at the finish on the 275.
You're running an auto? If so, your trans gearing is quite different.
There is one AutoX that I hit the limiter 3 times @ 6700 and I have at a couple others as well. I have a Strange 9", end of last year the 3.89 gear was toast. I just dropped off the center section this week to have a 3.70 installed. I've done all the work on my car, including a trans rebuilt, but I'm not messing with that thing. So, yes I decided to change the gear with the shorter tire. I don't think hitting the limiter a lot is a great idea.
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Autocross Tires 
