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Hoosier Product Bulletin

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While we're here. let's talk about "stagger" for a moment.
Back in the day when everyone had to run bias tires, there was a fairly large discrepancy in tire diameter, for this reason teams used to dig through the tire trailer and try to find tires with close to the same manufacture date in an attempt to gain some consistency. These days, even the manufacturers of bias ply short track tires, are pretty consistent, so much so that you can basically order your stagger, they make tires in like 1/2 inch increments so you can buy what you need. With radials, and I must have measured a million of them, the biggest difference in the same size tire was maybe 1/8 of an inch. So the concept of stagger, while valid, doesn't really apply to road race radial tires. The only way to provide for tire stagger would be to purchase different size tires, that is now illegal in IMSA and besides the fact that you won't get anywhere doing that on a road course, the tire sizes are so different, that you end up with all kinds of mismatched, crazy sizes that you can't tune to.
The idea of overinflating a tire and throwing it on top of the transporter to get the sun to "grow" it. also doesn't work, the radials simply don't grow anymore.
 

Fabman

Dances with Racecars
6,519
8,155
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
While we're here. let's talk about "stagger" for a moment.
Back in the day when everyone had to run bias tires, there was a fairly large discrepancy in tire diameter, for this reason teams used to dig through the tire trailer and try to find tires with close to the same manufacture date in an attempt to gain some consistency. These days, even the manufacturers of bias ply short track tires, are pretty consistent, so much so that you can basically order your stagger, they make tires in like 1/2 inch increments so you can buy what you need. With radials, and I must have measured a million of them, the biggest difference in the same size tire was maybe 1/8 of an inch. So the concept of stagger, while valid, doesn't really apply to road race radial tires. The only way to provide for tire stagger would be to purchase different size tires, that is now illegal in IMSA and besides the fact that you won't get anywhere doing that on a road course, the tire sizes are so different, that you end up with all kinds of mismatched, crazy sizes that you can't tune to.
The idea of overinflating a tire and throwing it on top of the transporter to get the sun to "grow" it. also doesn't work, the radials simply don't grow anymore.
Yes, I had a rotisserie I made back in the day. I could rotate 4 mounted tires at a time and the sun would reflect in the mirrored surface beneath it with 50 psi in the tires in the hot Sacramento summer sun. It worked like gangbusters, I could stretch the crap out of them....until after a couple heat cycles when they all normalized and went back to their original size-or close to it. That's when I started using air in the right rear (nitrogen in the rest) so as the tire temps climbed I would get more and more stagger. This worked awesome. No idea what they are doing these days. We all ran spools and bias plys, now they are on radials and there's all these fancy differentials....maybe stagger is a thing of the past?
 

Fabman

Dances with Racecars
6,519
8,155
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
6,363
8,187
getting off track, but still one of my favorite videos.. we used to have an asphalt oval series in Florida on 1/8, 1/4 and 1/2 mile tracks including high banks like Orlando and Lakeland, I loved it, you might as well tie wrap the gas pedal down and loosen it up as much as you could hang on to it, and let it eat. One of my proudest accomplishments was winning the Florida Short track oval series around 1992. mid 13 second lap times on a 1/4 mile is what about 67 MPH average.. lol what a blast.
BangShift.com Sprint Cars Racing Wheel To Wheel At Bristol
 

PAEracing

Paul's Automotive Engineering
Supporting Vendor
From our Hoosier rep, they have always told us that the hot pressure (aside from Daytona), should be 1psi for every 100# (for our 18" S75 racing slick). We typically start our pressures, for Mid-Ohio/Pitt Race at around 20-21psi cold and hot they're about 32-33 psi after a 40 minute race.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
8,425
8,356
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
Great info Brian, but could you clarify if you are discussing the pure Hoosier racing slick or the DOT Hoosier A7 or R7? I have a friend who runs a Viper ACR and like your example he starts way down there on his pure Hoosier slicks , but when he runs A7s he starts at a higher initial temp. I know I usually started around 24-25 with R7s and they would end up around 34-36 at the end of a race, but I have never run on Hoosier racing slicks. I have run Michelin slicks on a Viper and started them around 24 , so this info on the Hoosiers is valuable, since many of us are running them or have run them in DOT Comp form. Thanks.
 

PAEracing

Paul's Automotive Engineering
Supporting Vendor
Great info Brian, but could you clarify if you are discussing the pure Hoosier racing slick or the DOT Hoosier A7 or R7? I have a friend who runs a Viper ACR and like your example he starts way down there on his pure Hoosier slicks , but when he runs A7s he starts at a higher initial temp. I know I usually started around 24-25 with R7s and they would end up around 34-36 at the end of a race, but I have never run on Hoosier racing slicks. I have run Michelin slicks on a Viper and started them around 24 , so this info on the Hoosiers is valuable, since many of us are running them or have run them in DOT Comp form. Thanks.
I run the slick, not the A/R7. As far as the A7s when I ran Time Attack, we ran within a psi of the racing slick.

When talking about Daytona, the new racing slick can handle the extra psi. NASCAR tires are typically 60-70psi on the right side. It's the downforce on the banking that really heats a tire up
 

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