Tire pressure question?
Thread Starter
|
Junior User
Joined: Aug 2003
Posts: 50
Likes: 0
Tire pressure question?
i have a 2000 f-150 4x4 ext cab......anyway I am running 285/75/16 BFG's all terrain....I think there about the same as 33"12.50's.....My question what is the best pressure to run in these tires for a highway trip? i can feel a very slight vibration above 60......i've had them balanced and rotated and that helped alot....any suggestions?
Hotshot
Joined: Oct 2003
Posts: 17,791
Likes: 99
From: Ashland City, TN
what is the max rated on the tires?
Running your tires at max PSI isn't always the best thing to do.
Mine are rated at 35, and i'm going to move them down to 32 here in a bit. I had a discussion with my uncil about this. 1 lb of pressure in the tires makes the difference for a lot of things.
And remember, just because its max psi, dosn't mean thats where it is supposto be.
Your vibration could mean your due for a front end alignment.?
Missaligned tires can cause vibrations.
Running your tires at max PSI isn't always the best thing to do.
Mine are rated at 35, and i'm going to move them down to 32 here in a bit. I had a discussion with my uncil about this. 1 lb of pressure in the tires makes the difference for a lot of things.
And remember, just because its max psi, dosn't mean thats where it is supposto be.
Your vibration could mean your due for a front end alignment.?
Missaligned tires can cause vibrations.
Senior User
Joined: Mar 2001
Posts: 379
Likes: 0
There is an exact way to deturmine the proper pressure
Look on the door jam for the sticker that says the gross vehicle weight rating. It should have it broken down into front and rear ratings. Take the front number and divided it by 2 since you have 2 front wheels to support that weight. Take the number you got there and divide it by the maximum weight listed on the sidewall of your tire (this should be larger than 1/2 the GVW # off the door sticker). This should give you a decimal of some sort. Multiply this decimal number times the maximum pressure listed on the sidewall. The result of all of this is the proper pressure for the front. Repeat this for the rear. You can adjust the pressure higher or lower from there depending on your needs. If you rarely carry alot of weight decrease the pressure a couple of pounds, especialy in the rear. This will keep the tires from wearing down the center.
Look on the door jam for the sticker that says the gross vehicle weight rating. It should have it broken down into front and rear ratings. Take the front number and divided it by 2 since you have 2 front wheels to support that weight. Take the number you got there and divide it by the maximum weight listed on the sidewall of your tire (this should be larger than 1/2 the GVW # off the door sticker). This should give you a decimal of some sort. Multiply this decimal number times the maximum pressure listed on the sidewall. The result of all of this is the proper pressure for the front. Repeat this for the rear. You can adjust the pressure higher or lower from there depending on your needs. If you rarely carry alot of weight decrease the pressure a couple of pounds, especialy in the rear. This will keep the tires from wearing down the center.
Senior User
Joined: Apr 2003
Posts: 385
Likes: 0
What about the FORD recommended pres.
I initially liked your formulas, being an engineer. But I quickly realized that the values I was getting contradicted the DOOR pillar sticker placed there by Ford. On my Bronco 2 it is recommended to run 35 psi front and back. Using the formulas you mentioned returned 27 F psi and 30 R psi for my BFG AT ko's and 29 F psi and 33 R psi for my Goodyears street tires. Not unsafe numbers, but a little low on the fronts. I think that will produce excessive wear on the edges of the fronts for my BFG's. Thanks for the info, and food for thought, I can see some merrit in these formulas.
