Jay Lopez
Enthusiast
I'm going to run Hoosiers for the first time this weekend in Hallet, OK. Does anyone have any recommendations on a good tire pressure to start with cold?
Hoosier pressure recommendations?
- Thread starter Jay Lopez
- Start date
GTS Dean
Enthusiast
Got a pyrometer? Temperature is the best way to get the optimum pressure. Anywhere from 180-210F is a good range, with an even distribution across the tread. For a ballpark, look for mid- to upper-30s hot, then tune to suit your style.
MichaelThurston
Enthusiast
Check out the TireRack web site, they list all types of good info. Supposed to run a higher pressure in them.
99t1
Enthusiast
Supposedly they say 39-40 is the best but either my pressure guage is off (quite possible) or 26-27 seems better to me.
Nothing I ever did to any car was more noticable than going from streets to R1s many years back. That was only eclipsed by going from GForce (worse than old R1s) to Hoosiers.
Nothing I ever did to any car was more noticable than going from streets to R1s many years back. That was only eclipsed by going from GForce (worse than old R1s) to Hoosiers.
Frank Parise
VCA Venom Member
The purpose of adjusting air pressure is to properly shape the footprint (contact patch) of the tire against the road. As Deano points out, the tire pyrometer is the only legitimate tol to determine correctness of air pressures for each car and driver.
Friction between the tire and road surface creates the heat that makes your air pressures rise. The harder you accelerate, brake and corner the car, the more heat is created and the higher your air pressures will rise. Different drivers and different car set ups will create different heat scenarios.
To get the most grip out of the tire, you have to get it hot enough to be inside of its optimal temp range, not less and not more. Deano's numbers are good ones. When you take tire temps in pit lane, the temps have already cooled off considerably, possibly as much as much as 40 degrees or more. If you aren't up to at least 180 degrees on track (140 in pit lane), you're not working the tires hard enough to get them into their optimum grip range. If you're over 250 degrees (210 in pit lane), you are too hot and in danger of blistering the tires.
If you are constantly below the range, reduce tire pressures to create more heat unless the the pyrometer tells you you are already so low that you are riding on the rims. In this case, drive the car harder, use a softer tire compound, or try tennis instead. If you are constantly above the range, increase tire pressures unless the pyrometer tells you you are already so high that you are running on the middle of the tire only. In this case, drive smoother, stop sliding or skidding the car, or purchase some more life insurance.
26-27 PSI hot sounds OK for autocross since you can't build heat as quickly by driving the car hard. 38-43 PSI hot sounds like the optimum range for road racing. The tires will wear much better at high pressures. Personally, I find the Hoosiers to feel mushy and less precise below 38 PSI. I find them slippery above 43 PSI. I've also found that the stiffer you go on spring rates, the lower you go on air pressure to make the car dance. If you have stock spring rates, stay on the high side of the air pressure range. If you have have relatively stiff spring rates, say in excess of 500 lbs front and 800 pounds rear, I'd tend toward the low side of the range.
Balance the handling of the car by adjusting pressures differently in front than rear. If you stay within the prescribed temp range and air pressure range, you can reduce understeer by adding pressure to the front tires or reducing pressure to the rear. You can reduce oversteer by doing the opposite. I've found good results running as much as a 5 PSI hot difference between front and rear.
As for the BFG vs Hoosier, unless BFG has improved significantly since 1999, the Hoosier has been far superior than the "G-Farce". The old R-1 that preceded the G-Farce was superior to the G-Farce also.
If you want to go way fast, use new Goodyear slicks at $1,600 per set...the Goodyear scrubs aren't any better than a newish Hoosier, although they can be purchased for $300 per set instead of the Hoosiers at $1,000 per set.
Friction between the tire and road surface creates the heat that makes your air pressures rise. The harder you accelerate, brake and corner the car, the more heat is created and the higher your air pressures will rise. Different drivers and different car set ups will create different heat scenarios.
To get the most grip out of the tire, you have to get it hot enough to be inside of its optimal temp range, not less and not more. Deano's numbers are good ones. When you take tire temps in pit lane, the temps have already cooled off considerably, possibly as much as much as 40 degrees or more. If you aren't up to at least 180 degrees on track (140 in pit lane), you're not working the tires hard enough to get them into their optimum grip range. If you're over 250 degrees (210 in pit lane), you are too hot and in danger of blistering the tires.
If you are constantly below the range, reduce tire pressures to create more heat unless the the pyrometer tells you you are already so low that you are riding on the rims. In this case, drive the car harder, use a softer tire compound, or try tennis instead. If you are constantly above the range, increase tire pressures unless the pyrometer tells you you are already so high that you are running on the middle of the tire only. In this case, drive smoother, stop sliding or skidding the car, or purchase some more life insurance.
26-27 PSI hot sounds OK for autocross since you can't build heat as quickly by driving the car hard. 38-43 PSI hot sounds like the optimum range for road racing. The tires will wear much better at high pressures. Personally, I find the Hoosiers to feel mushy and less precise below 38 PSI. I find them slippery above 43 PSI. I've also found that the stiffer you go on spring rates, the lower you go on air pressure to make the car dance. If you have stock spring rates, stay on the high side of the air pressure range. If you have have relatively stiff spring rates, say in excess of 500 lbs front and 800 pounds rear, I'd tend toward the low side of the range.
Balance the handling of the car by adjusting pressures differently in front than rear. If you stay within the prescribed temp range and air pressure range, you can reduce understeer by adding pressure to the front tires or reducing pressure to the rear. You can reduce oversteer by doing the opposite. I've found good results running as much as a 5 PSI hot difference between front and rear.
As for the BFG vs Hoosier, unless BFG has improved significantly since 1999, the Hoosier has been far superior than the "G-Farce". The old R-1 that preceded the G-Farce was superior to the G-Farce also.
If you want to go way fast, use new Goodyear slicks at $1,600 per set...the Goodyear scrubs aren't any better than a newish Hoosier, although they can be purchased for $300 per set instead of the Hoosiers at $1,000 per set.
RockyTop
Enthusiast
Not to disagree with Dean and Frank (my heroes), but the convetional wisdom of having even tire temps across the tire's tread was called into question by Caroll Smith in his book "Drive to Win" saying that on bias tires, a properly set up car should have inside temps which are someting like 10 degrees (or maybe 15) higher than the outside temps, and on radial tires relatively more.
If I recall correctly, though maybe it's been to many beers ago, his reasoning was that on most tracks there are more straights than curves. The neg. camber causes heat to the tire's inner contact patch even while driving in a staight line. Consequently, a correctly set up car will exhibit more inside temp, declining across the tread surface as you move to the outside. Kinda makes sense.
My experience with Hoosiers on road courses has been similar to Frank's. At my home track of RoadAtlanta, my personal preference for feel and lap times seems to be about 40-42 in front and 36-38 rear. Hoosier suggests (for conservative safety or other reasons) that the tires should be in the 40-44 range (check my numbers at the Tire Rack's site which has Hoosier's tire care, break in and inflation pressure suggestions. They acknowledge that most people are tempted to lower their pressure due to the feeling of skating (especially before the tires are up to temperature), but they should not as they will be slower. Frankly, most of us mortal week-end warriors are not getting our tire temps up to the 180-220 range anyway.
If I recall correctly, though maybe it's been to many beers ago, his reasoning was that on most tracks there are more straights than curves. The neg. camber causes heat to the tire's inner contact patch even while driving in a staight line. Consequently, a correctly set up car will exhibit more inside temp, declining across the tread surface as you move to the outside. Kinda makes sense.
My experience with Hoosiers on road courses has been similar to Frank's. At my home track of RoadAtlanta, my personal preference for feel and lap times seems to be about 40-42 in front and 36-38 rear. Hoosier suggests (for conservative safety or other reasons) that the tires should be in the 40-44 range (check my numbers at the Tire Rack's site which has Hoosier's tire care, break in and inflation pressure suggestions. They acknowledge that most people are tempted to lower their pressure due to the feeling of skating (especially before the tires are up to temperature), but they should not as they will be slower. Frankly, most of us mortal week-end warriors are not getting our tire temps up to the 180-220 range anyway.
luc
Enthusiast
The best way to find the right pressure for YOUR car is to look for even wear on the tire.
The problems with doing it by temperature are:
1/ To be correct you have to do it before the tire have a chance to cool down,meaning not in the paddock but right in the hot pit.
2/ Due to the negatif camber effect,the inside of the tire,in a straight line,(as in usually the one before the pit),have more friction/contact with the track and therefore more heat.
3/In a turn, the outside edge of the tire will ALWAYS be hotter than the inside.At least at less than 4 degrees - camber.
What you want is the maximum contact patch available in turn,reason for - camber.
Also, for the same car weight, a bigger/wider tire will require less pressure than a smaller one.
All of my racer friends,as well than myself, run a lot less pressure than Hoosier or Tire Rack suggest.
And when we know that we have a good/even tire wear we check the pressure cold.
Whathever this # is, is what we use.
As an example on my Vintage race car,69 Mustang with 275/40/17 all around and a weight of 3200lbs,I use 21 in the rear and 25 in the front. Cold of course.
And it is a fast car with 650hp and time of 1.41 at Laguna Secca or 2.04 at Thunderhill.
Luc.
The problems with doing it by temperature are:
1/ To be correct you have to do it before the tire have a chance to cool down,meaning not in the paddock but right in the hot pit.
2/ Due to the negatif camber effect,the inside of the tire,in a straight line,(as in usually the one before the pit),have more friction/contact with the track and therefore more heat.
3/In a turn, the outside edge of the tire will ALWAYS be hotter than the inside.At least at less than 4 degrees - camber.
What you want is the maximum contact patch available in turn,reason for - camber.
Also, for the same car weight, a bigger/wider tire will require less pressure than a smaller one.
All of my racer friends,as well than myself, run a lot less pressure than Hoosier or Tire Rack suggest.
And when we know that we have a good/even tire wear we check the pressure cold.
Whathever this # is, is what we use.
As an example on my Vintage race car,69 Mustang with 275/40/17 all around and a weight of 3200lbs,I use 21 in the rear and 25 in the front. Cold of course.
And it is a fast car with 650hp and time of 1.41 at Laguna Secca or 2.04 at Thunderhill.
Luc.
Jim Hodel
Enthusiast
I must be running my Hoosiers at the wrong pressure or something (38 hot) because I did not see much of a difference between the Gforce R1a's and Hoosiers. I had expected a significant improvement because most people say the Hoosiers are better, but I did not see it. The new Hoosiers were better then the worn out Gforces, but as far as I could tell, about the same as the new R1a's.
My experience with these tires is on my modded Z28 not my Viper.
Jim
My experience with these tires is on my modded Z28 not my Viper.
Jim
