Tire Pressure (2023 Update)

I just got new tires installed, upon leaving the shop I stopped after the first block and I checked the tire pressure, it is 40 psi in all tires.

I let air out until they were 32 psi.

The car is a 1990 Lexus ES250; the recommended tire pressure is around 27-29 psi? The tire and wheel size is stock, 195/60/15.

Over the years, what I have always noticed about this car is that at 27-30 psi the front sidewalls sag or have a bit of a bulge in them, the bottom part of the sidewall just above the tire / ground contact point. Upon first glance they seem under inflated, however whenever I check them they are correct in the 27-30 range. Is this correct? Why the sidewall sag, is this due to the weight of the front? Or did the manufacturer spec the incorrect tire pressure?

Any ideas?

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Weight of the engine on the front. Sidewalls on radial tires will show a bulge due to the design of the tire itself. Totally normal. Manufacturer spec is designed for a LOT of factors, BUT it is only really good if you use the same size and make tire that the factory fitted as OEM. Simply because tires vary in many ways, even if they are sold as the same size and capacity. You can take a new Goodyear and a new Michelin both in 235-75-15 set them side by side and they will be measurably different.

Reply to
Steve W.

Many tire installers inflate tires to the maximum rated pressure, which is better than having them underinflated.

I wait until next morning and check them cold.

I try to inflate tires so that they wear evenly. Tires on a front drive car will require more pressure than the rear because there is much more weight (on an unloaded car) on the front than the rear. This will improve handling (less understeer) but is not a good idea on a fully loaded vehicle because you might have too much oversteer. Some tires e.g. Continental will require more pressure for even wear than others e.g. Michelin.

Reply to
Mike Walsh

Upon first

Looks can be deceiving. Use a good tire gauge (not always easy to find), inflate to a reasonable setting within the recommended range and dont pay too much attention to the appearance.

Reply to
HLS

Why would you use a different pressure than is indicated on the door of your car? I think you should check them cold, but cold in winter is different than cold in summer, so maybe every month or so.

Reply to
hubcit

Because many operators feel that "more is better". More air in the tires, a brighter TV picture, etc.

I myself allow up to 1-2psi above the pressure listed by the car mfg, particularly for winter. But no more.

I sometimes wish that tire mfgs would leave the maximum inflat. value off the tire sidewall, to discourage operators from referencing it when maintaining their tires. That maximum value just provides a "canvas", of sorts, for a wide variety applications. The same make and model of tire, with a max. inflat. value of 51psi, might see service under anything from a Ford Fiesta to a large Honda Pilot. Of course, the size and aspect ratio of that make & model tire will be different for those two examples, as well as the cold inflation pressure specified for each.

It's also critical to follow, at least closely, any 'offset' pressure requirements, EG, the GM Corvair, in its day, specified an 11psi offset from front to rear cold inflation(F: 15psi, R: 26). Those numbers represent values suitable for the non-radial bias ply tires of 50-60 years ago.

Today, many performance-oriented vehicles, such as from Porsche, BMW, and even Volvo, recommend different front and rear cold pressures. Those pressures were arrived at via hours, and even weeks, of combined calculations, road tests, tread wear and pyrometer analysis, coupled with the goal of arriving at pressures that are the best compromise between load capacity, handling, and comfort.

Varying from those pressures, EG: inflating all four tires to 40psi when only 34 might be specified in front, and 38 in back, or, inflating more than 2psi over or under the pressures in general, EG: 30 or 40psi on a vehicle calling for 33psi at all four corners.

Tires manufactured since 2000 are among the most advanced and safest in world automotive history, and are quite resilient and forgiving of even egregious pressure variations, up to 10psi above or below vehicle requirements, short term. And I emphasize short term, because, not just for wear to the tires themselves, but for reasons of vehicle safety and handling, such pressures should be corrected within a reasonable time of being noticed.

Reply to
TheTireWhisperer
**AMENDED - Version 2 please disregard prior submission **

Because many operators feel that "more is better". More air in the tires, a brighter TV picture, etc.

I myself allow up to 1-2psi above the pressure listed by the car mfg, particularly for winter. But no more.

I sometimes wish that tire mfgs would leave the maximum inflat. value off the tire sidewall, to discourage operators from referencing it when maintaining their tires. That maximum value just provides a "canvas", of sorts, for a wide variety of applications. The same make and model of tire, with a max. inflat. value of 51psi, might see service under anything from a Ford Fiesta to a large Honda Pilot. Of course, the size and aspect ratio of that make & model tire will be different for those two examples, as well as the cold inflation pressure specified for each.

It's also critical to follow, at least closely, any 'offset' pressure requirements, EG, the GM Corvair, in its day, specified an 11psi offset from front to rear cold inflation(F: 15psi, R: 26). Those numbers represent values suitable for the non-radial bias ply tires of 50-60 years ago.

Today, many performance-oriented vehicles, such as from Porsche, BMW, and even Volvo, recommend different front and rear cold pressures. Those pressures were arrived at via hours, and even weeks, of combined calculations, road tests, tread wear and pyrometer analysis, coupled with the goal of arriving at pressures that are the best compromise between load capacity, handling, and comfort.

Varying from those pressures, EG: inflating all four tires to 40psi when only 34 might be specified in front, and 38 in back, or, inflating more than 2psi over or under the pressures in general, EG: 30 or 40psi on a vehicle calling for 33psi at all four corners, might cause unexpected results during even ordinary day driving.

Tires manufactured since 2000 are among the most advanced and safest in world automotive history, and are quite resilient and forgiving of even egregious pressure variations, up to 10psi above or below vehicle requirements, short term. And I emphasize short term, because, not just for wear to the tires themselves, but for reasons of vehicle safety and handling, such pressures should be corrected within a reasonable time of being noticed.

Reply to
TheTireWhisperer

Oh yes, my uncle Ralph believed that you could never have too much air in your tires. He said "you just pump and pump and when no more air will go in, that's when you stop."

Surprisingly he died of disease, rather than in a terrible tire-related highway accident.

--scott

Reply to
Scott Dorsey

________

Don't know if you're joking or not, but it illustrates the ignorance and indifference toward the part of a vehicle that touches the road.

I prefer to follow instructions, at least as a starting point. And to use a good gauge to get there.

Reply to
Chris K-Man (Zickcermacity

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