HOME MAGAZINE FORUM RULES SPONSORS CONTACT
     
   
   
 
Go Back   CLASS RACER FORUM > Class Racer Forums > .90 Heads Up Class Racing Tech

Reply
 
Thread Tools Display Modes
Old 01-08-2019, 09:03 AM   #1
cal
Member
 
cal's Avatar
 
Join Date: Mar 2007
Location: southern md
Posts: 317
Likes: 1
Liked 1 Time in 1 Post
Send a message via AIM to cal
Default Air Pressure Front & Rear

Good Morning All.
Bringing Back this form.
OK here goes question # 2 & 3 & 4

What is your Slick Preference, and Why?

Front tire air pressure, What effect does raising & Lowering the air pressure in your front tire have on reaction Time & 60 ft time if any?

I realize all cars are different, and Hoosier, MT & Good Year will all Vary some.
What is a good Starting point for tire pressure?
How High can you go before tire spin starts in most cases?

Any other info you care to share on Tires & Pressure?

Just a 1st rd Duck looking for a win.
Cal SST 1177
cal is offline   Reply With Quote
Old 01-08-2019, 10:26 PM   #2
Tom Goldman
VIP Member
 
Tom Goldman's Avatar
 
Join Date: Jan 2003
Location: Allentown,PA
Posts: 2,121
Likes: 10
Liked 7 Times in 6 Posts
Default Re: Air Pressure Front & Rear

Well Cal ,this stuff is pretty much scienced out and pretty out in the open .
Bumping front pressure up or down can change RT'S a few thousandth's on fast cars , but the slower the car and bigger the tire ,usually the bigger the change is. ….But a hundredth in RT is usually about it, at least in my experience with .90 cars with small tires.
Bumping front pressure up will slightly lower the RT ,BUT ,60' should increase by nearly an equal amount.
I would never recommend going above 45# on our cars with small front tires ,the foot print just gets too small and the car gets "darty" down track.
Stockers blow them way up ,sometimes 50-55 # for heads up or record runs because it lowers the rolling resistance .
Rear tire pressure ,everybody's favorite subject , not so cut and dried . some run ridiculously low pressures and plant the rim into the ground so hard the sidewalls are shot in 20-30 runs.
Rule of thumb I've always followed is the smaller the tire is the more pressure it requires ,Larger tires ,less pressure. ….more weight ,more pressure.
You can have a car that murders the tree at 6# pressure but is inconsistent in 60' . ….Take the pressure to 7 1/2 -8# and the 60' is deadly but RT's fell off a bit.
I've run my 16x33 Hoosiers as high as 8 1/2# at 2250# in the car and they didn't spin.
Then you can adjust the shocks and start all over again !!!
__________________
Tom Goldman 1500 SG , 1506 STK
Tom Goldman is offline   Reply With Quote
Liked
Old 01-09-2019, 07:37 AM   #3
cal
Member
 
cal's Avatar
 
Join Date: Mar 2007
Location: southern md
Posts: 317
Likes: 1
Liked 1 Time in 1 Post
Send a message via AIM to cal
Default Re: Air Pressure Front & Rear

Quote:
Originally Posted by Tom Goldman View Post
Well Cal ,this stuff is pretty much scienced out and pretty out in the open .
Bumping front pressure up or down can change RT'S a few thousandth's on fast cars , but the slower the car and bigger the tire ,usually the bigger the change is. ….But a hundredth in RT is usually about it, at least in my experience with .90 cars with small tires.
Bumping front pressure up will slightly lower the RT ,BUT ,60' should increase by nearly an equal amount.
I would never recommend going above 45# on our cars with small front tires ,the foot print just gets too small and the car gets "darty" down track.
Stockers blow them way up ,sometimes 50-55 # for heads up or record runs because it lowers the rolling resistance .
Rear tire pressure ,everybody's favorite subject , not so cut and dried . some run ridiculously low pressures and plant the rim into the ground so hard the sidewalls are shot in 20-30 runs.
Rule of thumb I've always followed is the smaller the tire is the more pressure it requires ,Larger tires ,less pressure. ….more weight ,more pressure.
You can have a car that murders the tree at 6# pressure but is inconsistent in 60' . ….Take the pressure to 7 1/2 -8# and the 60' is deadly but RT's fell off a bit.
I've run my 16x33 Hoosiers as high as 8 1/2# at 2250# in the car and they didn't spin.
Then you can adjust the shocks and start all over again !!!
Thanks Tom.
Just trying to get some guys talking on here again.
Let the info flow per say.

Come on guys spread the info, even if it is basic stuff to you.
It may help a newbie somewhere down the road.

Just a 1st rd duck looking for a win.
Cal SST 1177
cal is offline   Reply With Quote
Old 01-12-2019, 10:45 PM   #4
Superstreet29
Junior Member
 
Join Date: Nov 2013
Posts: 20
Likes: 0
Liked 1 Time in 1 Post
Default Re: Air Pressure Front & Rear

My 33x16x15s like 10 lbs, even 11lbs at 2820 in S/st. Otherwise I just wad the tire then it flexes back on the stop.
Superstreet29 is offline   Reply With Quote
Liked
Old 01-27-2019, 07:15 PM   #5
Shake & Bake
Member
 
Join Date: Mar 2010
Posts: 206
Likes: 0
Liked 1 Time in 1 Post
Default Re: Air Pressure Front & Rear

Cal,
I run 8-lbs in my 33.5 x 17.0 x 16 Goodyear's. Any less than that and the inside sidewall wants to roll under the wheel.
Shake & Bake is offline   Reply With Quote
Old 01-29-2019, 03:02 AM   #6
Maverick
Member
 
Join Date: Dec 2010
Posts: 207
Likes: 0
Liked 0 Times in 0 Posts
Default Re: Air Pressure Front & Rear

So, my question is, in less ideal conditions where it is 85 degrees out and the sun in on the track, what do you do to make sure you don't slip the tire? Or does you car always hook since you throttle stop it at the line?
Maverick is offline   Reply With Quote
Old 01-29-2019, 09:35 PM   #7
Superstreet29
Junior Member
 
Join Date: Nov 2013
Posts: 20
Likes: 0
Liked 1 Time in 1 Post
Default Re: Air Pressure Front & Rear

That’s when you gotta adjust shocks
Superstreet29 is offline   Reply With Quote
Old 01-30-2019, 01:55 AM   #8
Maverick
Member
 
Join Date: Dec 2010
Posts: 207
Likes: 0
Liked 0 Times in 0 Posts
Default Re: Air Pressure Front & Rear

Just amazed that no one changes there tire pressure, when the track get hot. Always run the same pressure. I definetly don't know, but I run a smaller tire. I change my pressure from 6 1/2 to 8 , depending on the conditions.. They work around 8, but every now and then they will rotate 1/4 turn before they hook, then I back off the pressure. 32 X 14.

Last edited by Maverick; 01-30-2019 at 02:18 AM.
Maverick is offline   Reply With Quote
Old 02-12-2019, 01:07 AM   #9
doglover44
Senior Member
 
doglover44's Avatar
 
Join Date: Jun 2008
Location: New Carlisle OH
Posts: 534
Likes: 0
Liked 0 Times in 0 Posts
Default Re: Air Pressure Front & Rear

How long does a set of Slicks last in 9.90 racing !
__________________
Jake Biermann
doglover44 is offline   Reply With Quote
Old 02-12-2019, 08:27 AM   #10
1320racer
VIP Member
 
1320racer's Avatar
 
Join Date: Nov 2007
Location: New Jersey
Posts: 1,242
Likes: 7
Liked 84 Times in 28 Posts
Default Re: Air Pressure Front & Rear

depends if you have a tire deal or not.
1320racer is online now   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 01:04 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright © Class Racer.com. All Rights Reserved. Designated trademarks and brands are the property of their respective owners.Ad Management plugin by RedTyger