Tire pressure vs ride

I sometimes drop the pressure in Winter, to maybe 34, but I think the tire itself matters more than the pressure.

Has anyone at all said to inflate to the maximum? Was the tire you're using now on the market when your car was designed? Do you think that all makes and models of tire were tested by this hypothetical engineer...?

Well, some people do say to blindly "Inflate to the tire sidewall maximum", but thankfully it's getting rarer as knowledge is diffused. That maximum pressure is very rarely going to get you the optimum ride, traction and tread life, usually it will make things much worse.

If the car still has the exact OEM size and type tires on it, then the car maker recommendations on the door sticker are still valid. But people often switch to different size, speed rating or load rating tires and sometimes rim size is also changed, and then you need to (metaphorically) throw the car sticker out the window and go with the tire maker's Load & Pressure Chart as the primary reference.

The one thing that is important about the manufacturer label is any front/rear pressure biases, usually related to weight distribution in the vehicle - the tires at the heavier end of the car are usually kept higher. If you are figuring pressure for new tires place the same ratio of bias between the axles, even if the overall pressures are higher or lower because of the different tire type.

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The sticker the car manufacturer puts on the door regarding tire pressure is only for the tires that originally came on the car. When those tires are replaced, you should go with the tire manufacturer's recommendation on tire pressure. The weight-bias tire pressures between front and back might be different also. You can ball-park the pressure based on the max pressure on the sidewall or you can take the car to a grain elevator/truck scale and weigh the front and back axles. Then look up the recommended tire pressure for that weight. The tire dealer should have the pressure chart.

Jack

I can't find any. Tire dealer had no recommendation other than "30 pounds each", which they recommend for all cars to all people (great, huh?). If you can find a recommendation for TripleTreds on an '89 Grand Marquis I'm all ears.

The weight on my rear axle is definitely less than the weight on my front, I'm pretty sure even with the trunk and passenger compartment loaded to capacity. The manufacturer specified a bias of 4 PSI rear for all loads.

I know of one vehicle for sure where the factory recommended pressures aren't the best to choose even for the OE tires and that car is the '01-'03 Prius. The factory recommends 35 front 33 rear but many owners have noticed underinflation wear patterns such as edges wearing faster than the center at the factory pressures and have used higher pressures instead such as 40/38 or 42/40. Some have even foolishly exceeded the sidewall max cold ratings but I have not yet heard of anyone showing overinflation patterns such as center wearing faster. A side bonus to this seems to be increased fuel mileage

__________________ Not if you owned a 1996 Ford Contour GL as I once did, size P205-60R15. Front: 31psi Rear: 34.

Try ta figger that one out!

-CC

Understood. But just because one plus-sizes their tires, or, keeps the same size tire but goes up a speed rating or two - IE from S to T or V-rated, does not mean all common-sense goes out the window and the new tires are automatically set to the max. pressure placard on the tire. I just had an alignment done and the car was riding smooth - too smooth, in fact the tires were barely gripping the road! (sure enough, the alignment shop had inflated them to 35psi - I checked - they were 38-39psi hot). So basically NOBODY in this country knows how to set tire pressure!

I know my "new" Malibu(Saab-based) has a pretty hard suspension and actually rode better with the original S-rated tires. But I went ahead and got H-rated tires of the same spec. With the S-rated tires, I could inflate them up to 3psi over the door sticker(30psi), improve my rolling, and still have a smooth supple ride; with the H-rated Yokohamas - 31psi. Anything higher and the whole damn car rattles like Arlen Specter's jaw!

-CC

Do you know who manufactured the tires? If so, contact the manufacturer and ask for a chart.

I keep 40 front and 35 rear on my 2000 Grand Marquis. That seems to give the best tire wear but the ride is a bit rougher. The tire sidewall list 45 psi at max load.

Jack

TP whatever (Tire Pressure) was indebially painted on our Army vehicles.So was, Official only.One time I ''borrowed'' a Jeep to go to down town Saigon to viisit my Vietnamese girl friend for a few minutes.Al, in Mesquite,Texas said it was a good caper. cuhulin

_____________________

Just because one plus-sizes their tires or goes up a speed rating(IE from S to H or V rated) doesn't mean to throw common sense out the window and fill the tires to their maximum pressure as listed on the tire.

My 2005 Malibu(Saab based) came with S rated tires. The door placard said 30psi. I could go as high as 33 and still be comfortable with them and get better gas mileage. I recently upgraded to the same size tire, a Yokohama, but H-rated. Now I can go up only a pound or two over the door placard pressure. The Malibu has a hard suspension already, and going significantly above GM's recommendations is like riding the Coney Island Cyclone. Fun, but not as fun. 31psi is where they'll stay.

-CC