Tire Pressure for a Camry

They will be less safe as you have much less tread on the road, at the max rating you severly risk blowing out belts as there is little give to the tire. It will increase in pressure as it gets hot. Going back to 30-37 would be smartest. I blew out a new michelin going to 40 and it had a rating of 45, I broke a belt. Pressure is based on saftey and comfort, a balance.

Why do you say that? Have they changed the standards for a M&S tire for more than 3"of snow???

Maximum rated pressure is what it says: MAXIMUM. Not the expected normal operation pressure.

Similar situation is in electronic - they also have maximum allowed rating, but they have listed normal operation range... A chip designed to work at 5V will have maximum rating of 7V but it does not mean you power it with 7V - the difference between maximum rating and normal operation is the buffer zone for avoid failures.

Think of the other aspect - how acurate you think your pressure gauge is?

10%? Maybe... but maybe 15%? When was it calibrated for the last time? 10% of 45 is 4.5 - in worst case your measured pressure 45 is really 49.5psi, which is above manufacturer maximum!!!! And when you measured it on cold tires it might be much higher when driving high speed!

In your obsesion of saving tire thread life your are forgetting about your own safety - blown front tire at highway speed can be DEADLY.

messagenews:472f099a$0$11440$ snipped-for-privacy@roadrunner.com...

Is your pressure gauge tested to a calibrated unit, mine is and many repair shops etc are not, I throw away gauges that are wrong. You might be filling to 48 cold and hot tires could be 52lb. Best is lower them to a few lb over the cars rating. As I said I ruined Michelin.tires overinflating them

Huh?? You should always inflate your tires when cold

He infltes them to the max, which is wrong.

That was his point - pumped cold to the maximum will cause pressure go OVER the maximum when hot and you risk blowing up a tire due to overinflation.

I am guessing this question was for Charlie, not me ? :-)

If he is carrying a max load it is not. If he is m/t he's in trouble at max pressure.

I realize the OP said it was a 2000 model, so the following aside does not apply to his car. Was reading that 70 percent of the 2007 model year cars were required to have pressure monitoring tire valves. Was told they have a tolerance of +/- 5lbs before they turn on the warning light on the dash. My

2007 Camry has them. By 2008, all news cars will be required to have them, IIRC. When you change these to different size/type of tires, the valve units have to be recalibrated.

How is carrying max load help here?

A cold tire filled to max pressure with max load provides the same footprint as a m/t car at recomended pressure.

But putting max load on a tire with already maximum pressure will increase this pressure and might cause blow out...

This is not true. Tires usually say "maximum COLD inflation pressure." No company recommends adjusting the pressure of tires after you have driven a significant distance. The pressure increase do to heat build up as the vehicle is driven is already allowed for in the tire design.

Ed

With max load on a tire not inflated to max psi the increase of heat may cause failure. Further it will cause lack of control.

Actually the pressure inside the tire changes relatively little when you load it. If you don't believe me, jack the car off the ground, inflate the tires to the recommended pressure, then lower the car back on the ground. Your gauge won't be accurate enough to detect the difference. The pressure in the tire is related to the number of molecules of gas in the tire, the temperature of the gas in the tire, and the volume inside the tire. When you load the tire, the only thing that changes (until you start driving) is the volume of the tire. And although the shape of the tire will change when you load it, the actual volume changes very little. You just distort the shape of the tires until it is flat enough on the bottom to support the load. The envelope (perimeter) of the tire is defined by the steel cords that stiffen the tire. As long as you have a convex open shape, the interior volume doesn't change very much when you deform it. If you let all the air out you can flatten the tire enough to double the exterior walls back on themselves, and then the volume does change significantly. However, for a properly inflated tire the volume is close enough to constant that the typical tire pressure gauge won't be able to reliably detect any changes as a result of loading the tire.

So what is bad about loading a tire? Tires generate heat as they rotate because the sidewalls flex. The more you load a tire, the more the tire is flattened at the bottom to provide enough surface area to support the load at a given internal pressure. The more the tire is flattened, the more it flexed as it rotates. Running a higher pressure will actually reduce flexing and heat build up (and therefore pressure build up). So you should have no fear in inflating the tire to the maximum cold inflation pressure as long as you also don't over load the tire. However, increasing the pressure has negative effects as well. For tires load at less than the maximum load, you can cause rapid wear at the center of the tire. The tires are more sensitive to stone bruising. The vehicle may handle poorly if the pressures are to high. If you have the original size AND TYPE of tires on the vehicle, you should always follow the vehicle manufacturer's pressure recommendations. If you are going to deviate from these recommendation, adding 1 to 3 lbs extra probably won't hurt anything as long as you don't exceed the maximum cold inflation pressure listed on the tires sidewall, although you may (or may not) increase wear in the center of the tread.

Ed

There are load inflation pressure tables for all tires. For some tires, the maximum load is actually acheivable at a lower maximum pressure than listed on the sidewall as the maximum pressure. This is done so that higher pressures can be recommended by the vehicle manufacturer for high speed operation. From

"A standard lead tire with a normal inflation pressure of 35psi may be branded with a maximum inflation of 44 or 51 psi, indicating the tire's ability to meet special vehicle performance requirements. It does NOT increase the tire's load capacity. An extra load tire with a normal inflation pressure of 41 psi may be branded with a maximum inflation of 50-psi indicating the tire's ability to meet special vehicle performance requirements. It does not increase the tire's load capacity."

Ed

Let's not confuse high speed driving tires with a typical passenger tire.

The

== If you keep a close watch on tread wear and reduce pressure accordingly you may be OK - but sometimes tires take a "set" at certain pressures, so I'd be trying to get the right pressure early on. Perhaps try the chalk method so you don't have to wait for tread wear. I also like Yokohama, currently using AVID TRZ. I had kind of a harrowing experience with higher tire pressures I'd like to relate here. As I experimented for several years with the Camry using incremental changes, one day at apx. 70 mph, I turned quite quickly to move on to a highway transition to a different route, then corrected quickly back to center the car in the lane. Somehow, an odd oscillation started up, with the car lurching from side to side with subsequent corrections. This happened apx. four or five times and took total concentration to avoid loss of control. Temperature apx. 70 deg. F. road clear and dry. I've got the old 70 series aspect ratio 14 inch tires, but I run them at 28 front and 26 rear, rotated every 5,000 miles and that works best for me. Harder pressures are too hard and softer pressures too soft.