dmwhite

they were faster on the 9th heat cycle than on the 1st?

very different than my experience with hoosiers...

Bryan Watts

Very different than my experience with ANY TIRE EVER.

On a similar vein, I keep hearing this BS about Toyo's being faster just before they cord than they are when knew. Go tell that to a World Challenge team or even a front running Spec Miata team and see their reaction.

Bryan Watts

That's a lot of time for a set of tires...though you are compaing some of the fastest slicks with some of the slowest R-comps, it's still a LOT of time. How long was the course?

Whether you knew it or not, you car may have been better setup for the Dunlops than the Nittos. Therein lies the problem. Laptimes don't tell the entire story as setup for a particular car and tire combination can be worth a second or two on it's own and tracks can change by multiple seconds over the course of a day. Data acquisition, G's under cornering and braking, cornering speeds, etc all come into play.

Ultimately, if we're comparing the gap over a 5+ lap race, I'm definitely going to bet on the slicks to have a sizable advantage. If we're comparing fastest laptime, I'm less convinced that the slicks are going to have a huge edge over a Hoosier R-comp.

2BWise

Bryan, and Seth would know as well. How does driving a radial compare to a bias ply? My experience has solely been with slicks of a bias ply construction. I know that most slicks are radials and also know that the setup differences are night and day, but have never had a chance to actually test it. With the car setup for the tire what kind of differences, driving style and ultimate grip, have you seen between radials and bias ply?

Bryan Watts

Hard for me to compare bias-ply and radial slicks very well because they've been on two very different cars. All of my bias-ply experience was on a Formula Mazda. My radial experience is almost all from 2500 pound BMW's. I did get to drive a Formula Mazda once with radials, but it was only one session, so I'm not sure I can extrapolate much from it. IIRC, the Hoosier F2000 radials were the same size as the bias ply Hoosiers and Goodyears that we ran on FM's.

The biggest difference was that the radials felt more precise and less messy...the bias-ply tires felt a little sloppy at turn-in until they took a set and they liked pretty substantial slip angles. This difference could be seen just be following another car with radials while driving on bias-plys...our means of getting around a corner varied significantly. A Formula Mazda with bias-plys was actually tossed into the corner...sort of like you see in vintage Formula One videos. It made for some really exciting racing and scared the hell out of the F2000 guys we shared the track with on SCCA weekends. Once you got past the "sloppy" feeling, they had REALLY good feedback...you could always feel exactly what the tire was doing and when it was or wasn't happy.

I just remember being weirded out by the totally different alignment settings. I kept looking in my mirrors and thinking that the rear suspension must be broken because there was so much negative camber...with the bias ply slicks, we ran around 0 (actually, it may have been a bit positive) on the rear camber while the radials require a few degrees of negative.

hp18racer

2.2 mile course. I am sure the setup was better for the Dunlops. I ran a square setup with the Dunlops and got perfect balance. The Nittos were staggered and the car was understeering. There were two slow turns onto long straights, with the Dunlops I was 'on boost' in 2nd gear at corner exit, with the Nitto's I fell 'off boost'. I could definitely have closed the gap with some suspension tuning and adjusting my driving technique.

Bryan Watts

@ 2BWise - Are you required to run bias-plys in FSAE? For the tight auto-x competition ya'll run at those events, it seems like radials would "feel" a lot better in the transitions, but maybe the weight advantage of the bias-plys is more important?

2BWise

Your description of the bia ply tire generally follows what I've noticed, that they're numb at turn in but once you get settled in the corner have great feel. I've just never driven radials. Had the opportunity to run against a few cars with radials and they looked ridiculous since the alignment settings were outrageous, but was surprised how well they made it work.

2BWise

The biggest issue was that no one was offering a radial. Michelin now has one on the market but very few run it. The other factor was that we had a Goodyear sponsorship and they only had a bias ply that could be competitive. I learned quickly how to drive around it though and after 100+ hrs driving them have become very accustomed to making them work. Now that I'm done with school I have the opportunity to do things a bit differently and would like to drive something with radials to learn what kind of adjustments I have to make to get the most out of them.

Larry Herman

Mark, I'll help you with your dilemma. 1st out lap, Hoosiers will be faster. 2nd and subsequent laps, any slick will be faster. I have many years of time trialing under my belt to substantiate this general statement.

I will qualify this by asking what your point is? If it is for racing, then the above is usually true. If it is for time-trialing, then it is absolutely true because you should start your pressures a little higher as they will not build as much in 3 laps, so the slick is up to pressure even quicker than in a racing situation.

Veloce Raptor

Yeah, my experience is that they are good & consistent until cording, but not faster.







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Martin S.

True, true, the hardness numbers are relative and as I have been told very subjective. There is a little handheld device you can buy to rate and cross compare tires....

Regardless, money no object, Hoosiers. On a budget? The RA-1s are a real bargain for my 3,000 Lb 993 car.

Bryan Watts

It's a tire durometer. Have one in the trailer. Very helpful for when we ran a bunch of takeoff slicks to make sure that the fronts and rears we were running were of similar hardness, no matter what tire compound code was written on the side.

Greg Smith

Hmm, that's not consistent with what you've been posting for the past several years.

mark kibort

I think I agree, if anything, they are marginally slower when they are cooked and almost corded. Ive always drive to the track and practice and sometime qualify on the bald toyos. races always get the newer set. newer set, qual or race, always are faster by something under one second.

Another data point of this comparison is that the sicks in the race were running in the 1:30s after the first lap! the hooseirs were in the 1:33s after the first lap.
this was a cool day as well. Dont think there seems to be any difference in the two tires being warmed up better or worse than one another from the first laps.

mk










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