Just trying to make the most informed decisions possible regarding tire choice for next year so I thought this would a good place to ask.
Car is a mod class corolla,1800lbs with boost and around 200whp.Up here in the great white north we run only on asphalt with with courses under 1min in lenght.
I need to balance costs with performance,I have a set of light 13x7 aluminum race wheels so going with a 20x9.5x13 hoosier slick is a good option,I would like to go up to around a 22" tall tire to stretch 2nd gear a bit however.
With dot's I don't have as many choices,255x13 A6(need new wheels),275x15 A6(need new wheels)or maybe 225-50-14 A6 or 710's(need new wheels).
It's been suggested to me that with the light weight of the car the dot's aren't that great a match being designed for heavier cars,anyone have experience with the hoosier slicks in the R25B compound?.Would this compound be the 1 I'd want?.
Look forward to hearing your thoughts.
jgp1843
HalfDork
12/25/08 10:21 p.m.
A friend of mine used to run used slicks on his E Mod rotary-powered X1/9. He used Formula Atlantic qualifying tires. Because they were designed for a car with high downforce they were quite happy on a 1900 pound autocross car, and actualy had quite a long wear life. If I remember correctly, his were about 20 inch diameter, maybe 20.0x9.5x13, and he mounted them on 13 x 9 alloy rims. Best of all, the used slicks were cheap - like around $50 each, and had at least 50% tread remaining. I drove the car a few times (including at Nationals in 2002), and the tires handled great! The car weighed 1900 with around 180 hp at the flywheel.
For a taller tire, maybe rears for a FC?
I say used to in the above only because he has moved on to a 911. His nephew now has the X and is continuing to run the used slicks. I believe he bought his tires from one of the folks in GRM who advertize used slicks, back inthe classifieds.
Another advantage is weight - his tire/whel combination weighed around 19 pounds, about what a DOT tire weighs by itself. Since you already have lightweight wheels, saving around another 8 - 10 lbs per corner (and rotational weight, at that) is not to be sneezed at.
fifty
New Reader
12/25/08 10:45 p.m.
110HP here, FWD, 2100#. R25 Hoosiers are what I run, mostly because I get formula car take-offs for cheap (a set of 4 for around $100). Very sticky tire.
They are a cantilever design, if you run them at the common pressure of 18 - 20 psi, I find them to be really mushy. I'm running them at 30 psi, turn in is much improved at higher pressure.
Having run a high-powered, lightweight EP car (1580 lbs., 150 FWHP, Limited Slip,) on asphalt for 2 seasons, I'd definitely run R-comps over slicks. I was running R35's up front and R25's in the rear. R25's may have hooked better, but the R35's would barely last a full season, and I didn't have the dough to buy $1200 worth of tires per season. The only time the R35's got hot enough to stick on asphalt was in 90+ degree weather. Granted, in thse conditions, they STUCK, but otherwise they were pretty unresponsive. In temps below 60 degrees, forget it. Driving the car was like riding a jet-ski. I'd go for R-comps on cool asphalt.
My $.02.
PS: See also: Elam dominating EP by running on R-comps while everyone else ran slicks at nats once the surface changed to asphalt instead of concrete. Food for thought.
As you've found, with the wheels you have, tire choices are really limited.
I'd suggest to continue running the 20x9 cantilevers until you can replace the wheels. If you WANT a 22 inch tall tire AND your suspension has decent geometry, or can be adjusted to a decent geometry, and you drive a tight, low-slip angle line and/or have a lot of power - then I'd get the 275/35-15 A6 tires. If you have less perfect geometry and drive a deeper slip angle - get the 255/45-13 A6 tires. If you can PERFECT geometry and the car doesn't have a lot of squirt, get the 22x10x13 R25b tires.
Thanks for the thoughts,my wife co-drives occasionally(more this upcoming season)so I'm hoping to have a little more heat plus I was thinking of building a set of those super duper home depot insulating tire blankets.
The main reason for hesitating on buying new wheels(other than the obvious costs)is I might be tossing the entire suspension after next summer and designing stuff from scratch which includes a bolt pattern switch.
Poopshovel,how many eventsdid you do a season?just trying to gauge tire life,how many runs before the typical hoosier hardening?.
Poopshovel,how many eventsdid you do a season?just trying to gauge tire life
I'm guessing here. Around 12-14 when I was a little more active; 3 or 4 of which were 2 day events, and I did probably half of all said events with a codriver. Even with a codriver, the tires never felt as good as they did on a scorching hot day. Fronts didn't last an entire season. I was running 29-32 in the front (good wear and pyrometer tested,) and ~24 in the rear.
SkinnyG
New Reader
12/27/08 11:32 a.m.
I ran 20x9.5x13 Formula Atlantic slicks (Goodyear R175) on 13x10's on my 1275lb locost. Even on the hottest day with two drivers, I couldn't get the tires over 135°F and they need to be at least 160°. I will be downsizing to some 7 or 7.5" slicks to see if I can get more heat into them. They felt freaking awesome for the first 30 runs, then they seemed to fall off. I have probably 120 runs on them now and they are NOT wearing out..... They still stick better than my Sumitomo all seasons....
I ran a set of well worn V710's on 13x7's for a few events, and it was much more fun to drive but they still didn't get very hot.
The weight difference is very true. I can lift four slicks on 18lb wheels all bolted together onto the back of the 7 by myself. I need help with the 710's on 13x7's.
fifty
New Reader
12/27/08 1:34 p.m.
Good point about big tires and light cars - I've always had better grip when I ran with a co-driver. It takes a lot of autocrossing to get sufficient heat into the larger tires, and I'd guess that's somewhat independent of the rubber compound.
ncjay
New Reader
12/28/08 9:18 a.m.
Not sure if anyone's mentioned it yet, but you can always soak a slick tire with some tire softener. Purchase a durometer and start adding some Track Claw.
I'd be afraid of the tire agent turning the tires into hockey pucks after a heat cycle or 2 but have no experience with the stuff.
Skinny I ran the goodyear cantilevers in the softest compound a couple years ago and they weren't too bad on a hot day,I didn't do more than a hamdfull of events that year and tried them after carfull storage the next spring-they were toast as far as grip goes.
I think the hoosiers are softer than the goodyears though when new.