tire inflation?

Question

I noticed that the back tire of my Scion xA looked really low. I went to fill it up but it was very confusing. The owner's manual said inflate to 29 PSI. The tire said maximum inflation 44 PSI. (Quite a difference.) So here are the questions:

1) Should I trust the tire (44PSI) over the manual (29 PSI) because maybe they equipped it with a different tire?
2) When they say "max" (same on my bike tire) do you usually fill it close to the max or far below it?

Thanks

Answer 1

As usual there are a number of completely wrong answers and a few that are half right but none that quite get it. As the only person likely to answer your inquiry that actually WORKS IN THE TIRE INDUSTRY I think I can shed more light than heat on this issue.

Fundamentally, a tire is a container for air. It is the air in the tire that supports the weight of the vehicle, not the tire itself. How much air is in the tire determines how much load that tire can carry. The information molded into the sidewall of the tire is simply the tires load (wieght) carrying capacity at its maximum inflation pressure. This is in no way an indication of what the tire should be inflated to on yours or any other vehicle. The tire manufacturer doesn't necessarily even know what kind of vehicle that tire will go on. Neon's and Ford Escorts also use the same size tire as your car for example but they have different inflation requirements.

Toyota worked long and hard to come up with a tire pressure recommendation for your vehicle that provides adequate load carrying capacity along with good ride, handling, braking and wear characteristics. That would be the 29 psi figure found in your owners manual. Who knows more about your car than the people who engineered and built it?

Go with your owners manual, always check the tire pressures when the tires are cold (have not been driven on) at least once a month (preferably once a week) and never lower the pressure in a hot tire.

Answer 2

There's a lot of misguided information concerning tire pressure. The auto and tire manufacturers work closely together to determine the recommended tire pressure for any given vehicle, taking many factors into consideration, with safety being #1. The 44 psi you mention is the maximum amount the tire mfr wants to see in the tire under any circumstance. The 29 psi is the amount the car mfr has determined is the best average for safety, fuel economy, tire life, handling, etc. with the vehicle FULLY loaded. Check them COLD at least once a month.

Answer 3

First,I would go by the Owners manual. That is were Toyota has designed the suspension to ride the best. You could bring it up to the 44psi on the tire safely,although you will wear the center of the tread out on such a light weight car in a few 1000 miles, and every pebble you drive over will feel like a speed bump.
The max psi rating is used for many different vehicles,it is the maximum pressure the tire is designed for to give the highest weight caring capacity.

Answer 4

Stick with the recommended PSI in the owners manual. The max is the amount of air that the tire can safely hold.

Answer 5

Fill it to about 2 PSI below max recommended on the tire. Anything under that and it will start dragging your gas mileage down.

Also, get into the habit of checking what the tire says, not what the owner manual states. Eventually you are going to replace those tires and the PSI will probably be different.

Take care!

Answer 6

32 psi has been the "norm" for years on car tires. I'm sure the numerous engineers & safety reps with Toyota have done more research than can be found on Yahoo Answers. If they recommend 29 PSI that is what I would put in them.

Answer 7

i own a repair shop,and when they say max on them they usually mean no more than that at maximum load,meaning all the tires and car will carry or hold,usually on the tire it will say a good safe spot to run them 44 is too much ,and 27 isn't really enough,id run them at or around 32-35 ,and see how that feels,if there not running really low to the ground at 32,and it seems to ride good id leave it at that,like you said they aren't the original tired so the amount the book gives for it isn't going to be accurate unless you have the same type on it,also look on the door panel for the maintenance sticker ,sometimes it gives different specs also,good luck i hope this helps.

Answer 8

go by the manual or the sticker in the door jamb..never put 44 psi in a car tire. that is the most pressure you can put in it under heavy loads before it will fail

Answer 9

mister ss and dodgeman got it pretty good, 44 is the max, 35psi should be good, I run that in my corolla, basically same car, and it rides good and gives good fuel economy.

Lower psi = better traction, more wear, and less fuel economy

higher psi = better fuel economy, better treadwear, but sometimes can be a more bumpy ride

Answer 10

I would put between 30 and 35 lbs. in the tires and forget it.