Difference between chalk mark and actual roll out hoosier e-mod

[DIRT99]

Can anybody tell me what the average difference between chalk mark and actual roll out on Hoosier A and D 40 tires is? Thanks

[31bro]

Usually around 3" less the chalk mark

[RACEMAN]

Sorry guys, I'm not really following what's going on here. If you don't mind, could you please explain this to me. Thanks. RACEMAN

[stockcar5]

hoosiers are marked for size on the sidewall. when set to race pressures they measure less than what is marked. my guess is hoosier measures at a higher pressure than most of us race at.

[DIRT99]

This is the explanation from Hoosiers web site. Thanks for the reply on what u were seeing 31bro that's what I'm looking for. Anybody else that's doesn't know what we are talking about read this.

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).