Mazdax605
Mazdax605 UberDork
2/21/20 1:40 p.m.

Hey guys, 

 

I have a friend who puts the maximum amount of tire pressure that the tire is rated for on his cars and truck, rather than the rating by the manufacturer of the vehicle. It seems to me that this not wise, but he insists that a tire shop told him this is the proper way. I understand that the vehicle manufacturers pressure rating might not be the best for everyone, but running a tire at 50 psi on a Chevy HHR seems dumb. Is he right about this? Isn't he going to unevenly wear the tires? His other vehicle is a 2013 I think Avalanche. He always runs 50 psi in those as well. I imagine both ride rougher than they should with those pressures. 

daytonaer
daytonaer HalfDork
2/21/20 1:49 p.m.

I ran max recommended pressure on a set of tires for the boosted MPG. I achieved greater fuel mileage however all the tires failed prematurely.

 

I did not get odd wear patterns, I actually had tire failures at different intervals. I had tire "bubbles" form on the tread and sidewall.

 

I did not run the tires overloaded weight wise, but they did fail in the summer so I'm sure the heat contributed. 

 

Lesson learned for me was the 1-2 measurable MPG boost wasn't a savings over tires that lasted 5000 miles. And it rides way more "firm" when at max inflation pressures. 

classicJackets
classicJackets Dork
2/21/20 1:54 p.m.

In reply to Mazdax605 :

Vehicles are tested with tires at the pressure on the door tag. He can run with higher pressure, but it puts him outside the bounds of what the vehicle was expected to run with - might lead to higher loads into the suspension components (you'd be surprised how much pressure can change that), worse wear patterns as daytonaer commented, and an uncomfortable ride. Tire can handle that pressure, tire on vehicle at that pressure is not what any manufacturer (tire or vehicle) planned or tested to.

L5wolvesf
L5wolvesf Reader
2/21/20 1:56 p.m.

I've had a couple tire stores do this too. I got a BS response when asked about why. Overinflated will wear out the center tread quicker and is some conditions is dangerous.

The tag on the car is the correct pressures for the car's specs and the tires size(s) listed.

KyAllroad (Jeremy)
KyAllroad (Jeremy) UltimaDork
2/21/20 2:11 p.m.

The door tag is a good guideline but some vehicles missed the mark a bit.  90's Explorers come to mind where the sticker called for something like 26/24 psi.  Combine this (a low pressure intended to smooth out the ride in a small SUV with archaic suspension) with people ignoring their pressures and letting them drop into the teens......and you end up with blowouts.

Too high a pressure leads to internal strains on the tires (what does the PSI spike to when you hit a pothole?).  

Somewhere in the middle seems like where you should want to be.

81cpcamaro
81cpcamaro Dork
2/21/20 2:34 p.m.

I agree, door tags aren't always the best pressure. The VTX motorcycle I have recommends 33 front/36 rear, but most run them 38/40 or 40/40. Even Dunlop who made the OEM tires recommends the higher pressure, as it helps the tires ride better and last longer. Max pressure is 44 psi, so not at the limits.

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