Learn Me: crap can tires

I run a 1987 Mazda RX7 in Chump and Lemons. We started running this car earlier this year with some success.

A few things have sort of added up over time and now I am a little lost.

First, we started running 205 50 15 Star specs (did well, won a race) on 6.5" wheels.

Then we ran some 225 45 15 RS2 on the same 6.5" wide wheels (old tires I had laying around).

Then we ran some 225 45 15 Rivals on the same 6.5" wheels. These did pretty good, but did not wear as well as the star specs.

At this point, we ran some stiffer front springs (200 # up from stock of 90 #). I also cut a coil off the rear springs to increase their rate and drop the car a bit.

I had some 17" mustang wheels and some 1 year old star specs in 245 45 17 that we ran this past weekend.

The drivers side front tire wore fairly evenly the entire width, but it was shot at the end of the day. Day two, we ran some brand new (but scrubbed) rivals in the 225 45 15 size. We CORDED the drivers side front tire.

I guess my question is: What tires are you running on your crap can? What is the weight / drive wheels / tire life / pace of your crap can? Do you heat cycle your tires? What size tires do you run?

Thanks!

Rob R.

P.S. I am still trying to decide if the 245 17s are too much tire for the car. The car weighs 2400# empty.

We run the Star Specs 225 45 15 on 15x7 wheels on our Civic. They age out before they wear out. After two races, I put them on my DE car.

We used to run BFG supersports and had decent luck. The last race (which I didn't drive in) rivals were used and they got corded.

Tyler H wrote: We run the Star Specs 225 45 15 on 15x7 wheels on our Civic. They age out before they wear out. After two races, I put them on my DE car.

I have never seen 225 45 15 star specs. I would love to have had those.

They don't make star specs anymore. The new ZII doesn't come in a 225 45 15.

Poop.

Rob R.

In Chump/Lemons we run 225 Rivals on 7" wheels on the Miata and 205/225 StarSpecs on the '88 RX 7 on 6"/7". Personally I like the Rivals much more than the StarSpecs.

We see more rapid wear on the RX-7, but it's substantially heavier than the Miata, so that is expected.

Also... for us, keeping tires from cording is a game of:

• Bring more mounted tires than we need
• Keep an eye on tire wear
• Adjust camber to prevent the outside edge of the tire from cording
• Swap tires left-to-right to before they outer edge of tire is toast
• Find a tire shop who can flip tires on the rim during the race weekend

Those are good points. We usually have at least 8 usable tires for the weekend.

We have our camber set at about 2.8 deg. This gives us enough contact patch to brake and enough camber to corner without destroying the tires (usually).

Rob R.

Our team runs Rivals this year. I really like them, and they're wearing well (assuming no alignment issues). The only thing I noticed about them is they get greasy after a few really hot laps, so I need to back off for a lap or two.

We were just having a similar discussion on a local board. Check your toe, too much kills tires. Our alignment guru recommends -.2 at the most (-.1 on each side) for street use. At -.3 (autox/track setup) he'll apparently cord tires at 10k miles on his M3. Mustang driver chimed in that he has 2.5 negative camber, 8.5 of castor, and 0 toe, with very even tire wear on the street. Not sure its relavant but thought it'd be worth checking.

~36 hours of racing to a set of the Falken 615K's on our Camaro. We've probably got a good 6-700# on you, running a 255/45/17 on a 17x9 rim.

Wow, I don't remember what tires we've used (last time was the 615k's, but I don't remember before that), but we've never got more than 24 hours out of a set. This is on a stripped 2nd gen CRX.

the late '90's Golf I drove at the VIR 24hr. was on multi hr Rivals (don't know the size) ... they still had plenty of tread left after that race ... they had at least one other race on them ... I think they ran the same tires at the CMP Lemons in Aug

We eat front tires on our '88 RX-7. But then, we have more weight and less front tire than on the Miata (205 vs 225).

The Miata has 1.5 race weekends on a set of 225 Rivals. There's still tons of tread left. We'll get one more race weekend out of these tires, possibly more. I think the good tire life for the Miata is caused by lightness, better camber curves, and the fact that it doesn't reward over-driving.

Our 1.6 B6ZE powered RX-7 is so forgiving and so down on power that it begs you to flog the ever livin' E36 M3 out of it. So tires die young.

As for whether or not a 245 is too much tire. It probably is, but I'm coming to believe that too much tire is what you want for crapcan enduro racing. It's just that much more rubber under the car to soak up all the stupid you and your team mates can throw at it.

225 on a 6.5" wheel is a really wide tire on a narrow wheel. I wonder if that had anything to do with why the Rivals wore out so quickly. FWIW, Tirerack recommends that tire be mounted on a 7-8.5" wheel.

We ran Z2's at the last race on my 280zx (2400lbs, 225x50x16 on 7.5" wheels) and we'll have plenty of meat left for another race. We're one of the quicker cars on track (teens to low 20's out of 120 cars).

wvumtnbkr wrote:

Tyler H wrote: We run the Star Specs 225 45 15 on 15x7 wheels on our Civic. They age out before they wear out. After two races, I put them on my DE car.

I have never seen 225 45 15 star specs. I would love to have had those. They don't make star specs anymore. The new ZII doesn't come in a 225 45 15. Poop. Rob R.

I'll double check myself and report. They could be 205s.

I agree that the 225s on 6.5 is not ideal.

However, I have 10 of the 6.5 inch wheels.

poop again.

Rob R.

Does anybody have specific data regarding the Hankook RS3?

Thanks!

Rob R.

wvumtnbkr wrote: Does anybody have specific data regarding the Hankook RS3? Thanks! Rob R.

I run them on my MR2 and they're the best 'street' tire I've ever had. Treadwear is 140, and they have lasted all summer,including several track days and autox. One more track day at Barber left in them for Nov 2-3.

We ran the rs3 on the boat at summit this year, previously had dunlop z1 and ZII. We tried them as they are $20 less each than the others. Driving on a fresh set, I thought they had equal cornering grip to the dunlops and were easy to control, but that they had less braking/accelerating grip. The boat weighs about 2700, running a 245/40 17 on 17x8 wheels. We did wipe out the fronts from new to bald on Saturday, but I'm not sure that was the tires fault as we later found we had a worn idler arm in the steering.

We have run z1 and Rivals on the Civic and are pleased with the rivals, 2 full races with testing days and they still have another race in them, they are forgiving and predictable, with lots of grip in a big window to account for a variety of driver skill. 205/50 15 on 15x7, car weighs 2360 wet without a driver, all wheel drive. Wear has been nice and even, but we have -3.5 camber up front.

Treadwear on the RS3 is now 200 fyi.

Sonic: You think the RS3 did not wear as well as the dunlops or rivals?

Thanks,

Rob R.

Rob, it's hard to say for sure as we had a worn suspension part that may have screwed with the toe, but I do not think they wear as well as the dunlops or Rivals. We are about to get another set of tires for the boat, and despite the lower cost of the rs3, we are going to use Rivals or ZIIs.

crap. Why can't they make a 215 45 15 star spec? or even a ZII?

Crap.

Crap.

What would GRM do? The 17s or the 15s? What size for a 2400# rear wheel drive RX7 with 7 lb ft of torque (This matters because the 17s are WAY bigger and sap my powars.)

What tires then if you can in fact help me pick a size?

Crap.

Rob R.

I would find some 15x8 wheels that will fit and run 225 Rivals, or 16x8 wheels and run 225/45 Dunlop ZII. You are a fast class A car, and need every advantage you can get.

Otherwise, just go back to 205/50/15 on the wheels you have a lot of and try to adjust the loose nuts behind the wheel to save the tires

Sonic wrote: We have run z1 and Rivals on the Civic and are pleased with the rivals, 2 full races with testing days and they still have another race in them, they are forgiving and predictable, with lots of grip in a big window to account for a variety of driver skill. 205/50 15 on 15x7, car weighs 2360 wet without a driver, all wheel drive. Wear has been nice and even, but we have -3.5 camber up front.

?

One of the increasingly rare all wheel drive Civic wagons, complete with 6 speed transmission (it has a super low gear shorter than first, for rock crawling or mudding or something. We use it to drive on the trailer carefully).