Hoosier Tire Mid-Atlantic

[KevinGale]

Not sure if Sherm was talking 1/2" diameter or circumference. Circle track cars that just turn left often use a spool and stagger in the rear tires. It makes the car turn left better. There is a lot of fine turning in the amount of stagger. So stock car tires tend to come in slightly diameters so they have different amounts of stagger. So supposedly identical rear tires may be different sizes. When I buy tires I have to look at the markings that are written on tire with some type of tire pen to make sure I get tires with the same circumference. Another reason I like picking them out by hand.

The strange thing is that the circumference isn't a spec that you can order. Or at least I haven't been able to do that. It seems like the different sizes are just mixed together. Maybe the quality control in this area isn't high since having different sizes is good for stagger choices. I don't know. John Reed or Sherm might know.

Also this doesn't just apply the to rear tires. The fronts can have stagger also. This affects how the car turns under braking. Putting stagger in the front can apparently help the car turn in under braking.

[sdwarf36]

Circumference. The spec Hoosier we had to run had 235+ 215 series-about a 2" spread between them. Although you could get a 215 that was as tall or taller than a 235. The well to do racers had stacks of tires to get the numbers they want. The poor would be doing things like overinflating the tire+ setting it out in the sun. At least with dirt, tire press. wasn't as importiant. You could fudge things a bit to get the stagger you wanted.
Front stagger isn't as importiant. Our LF was so light (or in the air) and if you want quicker turn in, you block off the rf brake.
I dunno if it has to do with the size of my car, or that I'm just so used to anything it does, but can feel a 1/2".
And how importiant are the right tires? Between the A-R slicks + the Hoosier "dirt strockers" (my wet tires) 3.5 seconds on Okemo.

[sachilles]

Sure you can feel stagger differences in your race car, but can't tell when the wheels are off center on your bus.

[walterclark]

The 8 Hoosier DOT-R tires I just got have the same circumferences within the two models - or at least near enough to the same that my measurement repeatability was worse than the difference.

[Chief Geek]

doing things like overinflating the tire+ setting it out in the sun

Please tell me we're talking about non-radials. Otherwise, I'm terribly confused (more than usual).

Paul

[KevinGale]

Bias Ply. Here is some info from Hoosier which explains why I have to look at the yellow chalk marks when I pick out tires. When I have ordered from Hoosier Tire East I was able to talk to the guy taking the order and explain I wanted no stagger. They were good and just picked fronts and backs with matching chalk numbers.

2. What is the number written on my bias race tire in yellow chalk?

As a result of a tire being bias in design (as opposed to radial), it will have a circumference that varies from tire to tire. This is not something that is unique to Hoosier but is common to all bias tire manufacturers. However, Hoosier has went to the expense of placing a "chalk-mark" on its bias ply tires in an attempt to assist the consumer in making the proper selection when purchasing new tires. It is something Hoosier does that our competition does not. Now, to understand its use, you need to understand a little of the manufacturing process as well.

After a tire is cured, it is removed from the press and placed on a machine called a "post-inflator". On this machine each tire has air injected into it for a set period of time. The amount of air is determined by our engineering department and is not the same for every type of tire Hoosier produces. After a set time period, a tire is then measured and the circumference is recorded. Then a press operator writes the size on the side of treaded tires and on the tread of slicks, in yellow chalk. All Hoosier bias ply tires with a chalk-mark, follow this same process.

Now, how should the chalk mark be interpreted? It should be viewed as a reference point or a guide on purchasing tires by size to attempt to attain a certain stagger. Say for instance, you needed to replace your right front tire. Your car currently has 1" of stagger (with the RF @ 28 p.s.i.) but you want to get 1 1/2" of stagger. The tire you were replacing had an original chalk mark of 86", and had a roll out, of say, 85". Obviously, you would want to purchase a tire bigger than the 86" tire you removed. Most likely, a tire with a chalk-mark of 86 1/2". You have to remember there are many factors that go into what size a tire will actually measure. The ambient temperature that day, the air pressure in the tire, whether the tire is new or old. These are factors that no, one person, controls. You just need to be aware of their existence and work with what you know. The chalk mark does not tell you the circumference of the tire at running pressure, it does not tell you how big a tire will grow to, it tells you that a tire is either going to be bigger or smaller than another one with a different chalk mark. It's just that simple. Bias ply tires, by nature, are going to vary in size, whether you buy a Hoosier or the competition's tire. By keeping good records, using common sense and understanding how the chalk-mark Hoosier tires provide, you will be step ahead in selecting the proper sized tire(s)