Max Tire Pressure

Tires are designed to run with some deflection due to the weight of the vehicle. If you get too far away from this shape, the tire will wear unevenly (toward the edges, for too low pressure, and wear only in the center if too much pressure). Since tire deflection is determined by the weight of the car, tire pressure is determined by the car weight - the pressure on the door jamb. The pressure on the tire indicates the maximum the tire will withstand, and dictates the heaviest vehicle the tires will perform on. There is room for adjustment though - higher pressure equals tighter handling response and better fuel economy on smooth roads. On bumpy or low-traction surfaces, I would stay with the door jamb pressure unless I'm sure I won't drive at highway speeds in that condition. As long as you aren't causing uneven wear, a higher pressure is fine. My Maxima suggests an extra 5 psi for mostly highway driving, so I suggest a compromise and go with +5. If you want better handling, try a higher-performance tire that is built more solidly.

Dave

Thanks Dave, I'd say 90% of my miles are on the highway, so maybe I ought to stick with the tire's stated max (44 PSI). I took a look at the door jamb and it looks like it's recommending 26 PSI (cold). A difference of about 70% between the door jamb pressure and the max still seems like a lot to me. I've got about 65K miles on the tires and so far they look fine.

Thanks again,

-Scott

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The door as I have been told by various vehicle and tire manufacturers.

Personally, I'd run at 35-40psi in your situation. I like to have some margin against increased temperatures on hot days.

Dave

Exactly. Check your pressure first thing in the morning. Drive a few miles. Check again. It will be up 5 pounds, even on a cool day.

The pressure on the tire is the absolute max and was never intended to be the "running" pressure. While you can probably go 5 lbs over the door sticker, you should stay 5 lbs under the max as an absolute limit.

If you have 65K miles on these tires and they are wearing evenly, the pressure you are using is close to ideal. Most of us are lucky to get half that. I wouldn't change anything.

Have you ever had a blowout? If not, I'm honestly surprised. If the door jamb says 26 psi, the ideal tire pressure for the vehicle is 26 psi. However, since you've been running them so long at 40+ psi, 26 psi at this stage would make them feel very underinflated. I'd back it off to 33-35 psi

*max*, and then keep it at 30 or so on your next set of tires (which I'd be inclined to purchase sooner rather than later...).

The number on the door jamb, as mentioned by other posters, is so low for multiple reasons. It's the number Nissan feels the vehicle handles safely at (i.e. less chance of rollover), and will attain the fuel economy they publish. It's not all about handling and tire wear. Personally I over-inflate my Maxima's tires by 1-2 psi over Nissan's recommendation, but that's it.

As long as you stay at or under the max cold inflation pressure on the tires, you are not incurring any increased risk of a blowout. I have always found the number on the door jamb to be an absolute minimum, below which the car/truck eats tires as fast as you can buy them and handles like crap.

That might be true... but more than 5 lbs above I find gives a very bouncy feel to the ride/handling.

Reading this post, I remembered all the Ford Explorer / Firestone Tire rollovers from a few years ago. Ford decked out the Explorer with the same Firestones they were putting on the Ranger, but the ride was too harsh in the heavier Explorer. Their solution was to underinflate the tires, with disastrous results.

I'm not saying this is history repeating itself, or that Frontiers with tires at 26 PSI are rolling like Suzukis... it's just the first thing I thought of. Though, your tires max PSI of 44 seems pretty high. Don't most cars/tires typically call for somewhere around 30-35 PSI? In which case 26 seems a little low, but not unreasonable considering the weight of the vehicle.

Scott McKnight wrote in news: snipped-for-privacy@4ax.com: