Tire Pressure

a.k.a. Patrick · 04-03-05, 09:34

Do you follow the pressure recommendations on the tire, or the vehicle manufacturers pressure recommendations on the door jamb.....

JDookie · 04-03-05, 09:39

I follow the manufacturer recommendation because all that's on the tire is the max pressure, not the recommended pressure for your application.

White95Max · 04-03-05, 09:40

It depends. I fill my tires higher when I'm going on a trip on long straight roads. I get better gas mileage that way. Of course I never exceed the maximum pressure on the sidewall, I never even go within a few PSI of that #.
I usually have them filled a few pounds above the vehicle manufacturer's recommendations.
My current tires have a MAX PSI rating of 44. I usually have them at 35 all around. I believe the manufacturer's rec is 32F 33R.

SpoiledMan · 04-03-05, 10:14

The tires on my car are *very* different from what came on there so I adjust the pressure to my driving style and keep in mind the max pressure on the sidewall. With the short sidewalls on my tires, I also keep rim protection in mind. This all leaves me with 42 in the fronts and 39-40 in the rear.

JDookie · 04-03-05, 10:20

35psi all around is a good rule of thumb. I wouldn't run anything less than that. If you remember all the problems Ford was having with the Explorers, I think the majority of the problems originated from having a recommended tire pressure that was actually too low for that application. In order to achieve a softer ride Ford was only recommending something like 30 psi, and that's just too low.

On the other hand, if you run a pressure to high it will prematurely wear the insides of your tire treads since they will be mostly riding on the center of the tire instead of evenly across the whole tread.

Passenger cars should be set at a pressure and kept that way, trucks on the other hand can be played with. The front tires are carrying the load of the passenger and the engine which is consistent and the tire pressures should stay exactly what is recoomended but the rear tires sometimes carry a load and sometimes don't, but the manufacturer has to assume that you ARE carrying a load so they give a set pressure recommendation based on that assumption. This usually means that you are running too much air in your rear tires 75% of the time.
The F250 I used to own had a front pressure of 55psi and a rear pressure of 80psi which was WAY too much for normal *unloaded* driving so lowered the rear pressure down to 45psi for normal driving and bumped it up and down as needed. When towing, I put it all the way to the recommended 80psi, but never any other time and no problems at all with premature wear.

JustinTRW · 04-03-05, 10:29

I follow the manufacturer's recommendation because it takes the vehicle specific application more into consideration. However, when you start playing with different tire brands and different compounds (Dot legal R-compounds for instance), things can change. It's best to figure out what works best.

For example, on my Merc, 32/f and 35/r is recommended on the door jam. But I run 35 all around because the front tire tends to roll over during hard cornering due to a lack of negative camber. This gives me a touch less understeer and is a good compromise, short of pulling out the pyrometer.

On my Lotus, I follow the manufacturer's recommendation exactly. 26/28psi or something like that. Works great for street and performance driving.

Tailor the pressure to your specific application!

SpoiledMan · 04-03-05, 10:51

Quote:

Originally posted by JDookie
On the other hand, if you run a pressure to high it will prematurely wear the insides of your tire treads since they will be mostly riding on the center of the tire instead of evenly across the whole tread.

Over inflation wears the middle of the tire. Under inflation wears the edges.

sQuashed · 04-04-05, 05:21

In different words, thats what JDookie said

kartoon · 04-04-05, 06:27

I only follow the vehicle manufacturer's recommendations.

The tire manufacturer does not know the kind of vehicle, load and other factors. They usually specify optimum or maximum tire pressure.

MartyGrant · 04-04-05, 07:34

Toyota says 27/28. (On a pick-up!). Wear patterns showed they were too low so I go +3...then I add 2-4 because of higher temperatures, load and higer speeds.

I use the recommended 30/32 on the Accord.

HRP · 04-04-05, 02:35

The car manufactureres use the tires as a part of the ride adjustment. This allows the more sophisticated driver some leeway in choosing a softer or firmer ride with the attendant changes in the way the car handles. As mentioned in an earlier post, lower than ideal pressure will cause excessive wear at the outer edges of the tread; higher pressure, wear at the center. I understand that the highway patrol generally prefers higher pressures to augment the handling characteristics, but a high percentage of their driving is at highway speeds. I run my heavier cars 3500 lbs and up at 36 lbs (measured cold). As mentioned above: Taylor your pressure (within the specs of the tire) to the specific application and your preference in ride and handling.

bet993 · 04-04-05, 04:24

I am sorry I have to disagree to a point with some of this discussion. There is no good general rule for tire pressures, except to follow the manufacturer’s recommended tire pressure for the original equipment on the vehicle.

Each vehicle and application is unique. Tire construction, wheel size, driving conditions, temperatures, etc. all play important roles in determining what the proper tire pressures should be. Some vehicles even have different pressure for front and rear. Notwithstanding, the effect the pressure has on the wear of a tire, adjusting the tire pressures effects the handling of the vehicle, which can result in more over-steer or under-steer.

Not to pick on JDookie but 35psi is not a good round number to just throw out to the general public. 35 psi on the 18” rear wheels, of my rear engined 996 would result in rim damage and/or tire damage on all but the sedatest driving and/or on the smoothest roads. The factory recommendations for the rear tires on my car are 44 psi (fronts are 36psi).

The biggest problem with discussions like this on a board like Autopia is the vast differences in cars and applications being used. What is good for the corvette owner is not good for the Honda accord owner, which isn’t good for the Honda accord owner with aftermarket 19” rims, which is not good for the F150 owner, etc.