Running 40 PSI vs 35

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322
Location
Tennessee
Thread starter
Some people on another forum claim they run 40 PSI in the Prius C tires and supposedly get 20k more miles on their tires than the tires are rated for. I'm running 40 PSI now and I I kind of like the way it rides and handles. I do mostly around town driving and less than 5k miles a year. Do many of you here run more PSI than the tires call for?
 
Messages
16,409
Location
NH
More than the tires state, or more than the placard on the door jam? The tires state their maximum, and I would not run past that. Ever. As to the door jam, it depends. Yes I have, and on some cars it does feel better. If the tires don't wear badly as a result, I will keep it there. But on my two Camry's I found the door jam's 30 (or 32) psi to actually work best, so, I've been content. On my truck I did bump the rear tires from 32 to 40+ BUT at the time I was towing an indeterminate amount of weight and it felt sloppy--extra psi fixed that. [Short distance move, wasn't going to run to a weigh station out of my way.] 30 psi feels kinda sloppy in that but tire wear is ok so... shrug Lastly, on my Jetta I found it felt best at 40psi, give or take--but when I tried that with snow tires it wandered all over the place, and I had to reduce the pressure. At 5k per year I don't think you'll see the extra tire life (tires apt to age out rather than wear out), and there is a risk of reduce traction in wet (IIRC wet traction may suffer, less contact patch). I don't think it really matters either way for you, so, no harm no foul.
 
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820
Location
Upper midwest
I run 38 to 39 cold which can gets me 40 to 41+ hot for "sport driving", spring, summer and fall, on my car. I could never go by the low figure on the door, I would be rolling over my sidewall on a daily basis and have horrible handling. I wear my tires tire evenly for the most part, with the exception of the outside outer edge is pretty worn at the end of the tire life, even with 1.5 deg negative camber.
 
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10,425
Location
Cincinnati, OH, USA
I usually do better at max sidewall rated pressure (on a passenger car), mainly because I do a fair amount of hills, city, & stop/go driving. Now, if you do all highway straight line driving, you may wear the center quicker than the edges-but I've never had that problem. I don't think 5 PSI extra would hurt anything, personally.
 
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35,779
Location
ME
Yeah I run around 38 on my prii. Stiffer sidewalls. Little chirp when I gun it in a corner. Good even wear.
 
Messages
570
Location
Alberta
On my work truck I run them at 33 - 35 psi instead of the recommended 40 psi for a better ride on gravel roads, and actually get more miles out of a set as well. The gravel doesn't chew the tread up as quickly at the lower pressure. I don't even notice the low pressure light on the dash anymore smile
 

Pew

Messages
956
Location
Illinois
Depends on the car and tire. The evo was 32psi IIRC but I normally ran 34psi front and 36 rear on it. In the focus I just run it at the factory 36psi unless it's a super soft sidewall tire like the RT43s, then I run 38 since the sidewalls on those tires is ridiculously soft. I haven't noticed any abnormal wear with the RT43s and the OEM Cooper RS-3A, but my previous set of tires with 50K on them, the Sumitomo HTR A/S P02, had worn the center treads significantly more than the outside at 38psi with 90% highway driving.
 
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6,415
Location
Wet side WA
My Hankook tires are rated at 51 PSI I run them at 40 PSI rather than the 32-34 factory. My tire wear seems to doing excellent and I get about 2.5 more MPG in the City and about 4 more MPG on freeway trips.
 
Messages
9,833
Location
OH
I've tried running at the max listed on the sidewall, and running 5 PSI over the pressure listed on the door. Running max pressure provided a ride that was way too rough. Running at 5 over the door jam pressure was fine....
 
Messages
14,885
Location
NE,Ohio
The elantra is 32psi iirc but I usually keep it around 35psi on warm days.. so in cold morning it might be closer to that 32psi. the jeep requires 36psi but other cherokee models run 32psi with smaller tires so it appears to mainly be for MPG. I usually keep it around 36 when warmed up, but if it goes over 40 the ride is terrible and I let out a couple psi.. I dont add until its under 34psi in morning
 

JHZR2

Staff member
Messages
44,286
Location
New Jersey
I usually air up around +5 unless the car already specified over 40 psi. I always get great tire life.
 
Messages
1,423
Location
MN
My Volt calls for 38 PSI, I run it around 42 cold which even on the hottest day rises to about 45-46 when driving. Well within the limits of the tires. Manufacturers test their tires WELL beyond the "Max PSI" rating on the sidewall, I have no doubts that my 45 PSI max-rated tired can handle 1-2% over their rating when hot. I'm running the Firestone FR710's that were almost new when I bought the car. I can't tell you how much I detest these tires, but they just wear like steel and I can't bring myself to replace perfectly good rubber. When inflated to the above-mentioned pressure, they really do wear evenly and I've had no issues with cupping or camber wear. I rotate every 5k miles (front to back, no cross rotating), and all 4 tires are almost identical in wear.
 
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Messages
2,176
Location
Flaherty, KY
I typically run about +4 PSI over what the door jamb label indicates. I find that gives me the best combination of ride quality, fuel economy and treadwear. Usually before a cross country trip I'll air up a little higher than that, mostly because of extra weight with four kids & luggage, plus for the marginal fuel economy benefit.
 
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2,942
Location
Western S.C.
Originally Posted by Eddie
... If you up the pressure 10% or so ... usually the foot print drops so hydroplaning becomes an issue.
No
 
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Messages
9,833
Location
OH
Originally Posted by zfasts03
It's tougher on suspension components.
Maybe if you inflate to max pressure as listed on the tire, but running at the recommended pressure +5, I don't think this is true...
 
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