Tire pressure?

[cpacini]

I bought a new set of tires today, when I got home I checked the tire pressure and the shop had inflated them to 40 psi. The tires list 51 psi max on the side wall. I've always inflated to the max psi listed on the tires, but 51 seems high (the set they replaced said 35).

Is it safe to keep the tires at 40, or should I inflate them higher?

The tires are Sumitomo tour plus ls, 215/55R17

 

[Greenman]

Our resident tire pressure expert has been banned, so we'll never know the right answer. But if it was me, I'd look at the tag on the drivers door jamb for what the manufacturer wants.

 

[MongGrel]

I'd probably leave them where they are.

Max is just max.

I'll be corrected, I imagine.

40 should be fine, about where I keep mine.

 

[Zenmervolt]

You should use the pressures listed in the owner's manual for your car. These pressures are also typically listed on a sticker either on the driver's doorjamb or on the back side of the fuel filler door (the latter being more common with European cars).

The pressure listed on the sidewall of the tires is just the maximum they can hold; it's an engineering number, not a recommendation for what you should run the tires at.

ZV

 

[dguy6789]

The car manual/door recommended PSI is a good place to be at, but the number tends to be conservative and favor softer tires for a smoother ride in my experience. I wouldn't ever run a tire at what the tire says it can do at max however.

 

[desy]

INFLATE TO SIDEWALL
Just for those who remember
Seriously, inflate to what the car door specs say or a couple of pounds above to improve mileage

 

[Muadib]

You should use the pressures listed in the owner's manual for your car. These pressures are also typically listed on a sticker either on the driver's doorjamb or on the back side of the fuel filler door (the latter being more common with European cars).

The pressure listed on the sidewall of the tires is just the maximum they can hold; it's an engineering number, not a recommendation for what you should run the tires at.

ZV

I thought that number was only for the original set, and so I only used it as a guide once I got new tires? Am I wrong?

 

[ElFenix]

I thought that number was only for the original set, and so I only used it as a guide once I got new tires? Am I wrong?

as long as you keep the same size and load rating it's the same pressure.


here's a post with adjustments for load ratings:

http://www.mr2spyder.net/spyderweb/index.php?/topic/520-tire-psi-and-load-rating/

 

[kitatech]

Start at doorjamb specs and increase by 2psi to suit your preference

...the higher the psi the firmer the ride and quicker the response...max sidewall PSI is @ MAX load capacity...

Ultra performance tires perform better @ higher PSI than touring tires that are made for a soft cushy ride...

 

[Muadib]

as long as you keep the same size and load rating it's the same pressure.


here's a post with adjustments for load ratings:

http://www.mr2spyder.net/spyderweb/index.php?/topic/520-tire-psi-and-load-rating/

I don't know anyone who buys tires based on load rating. Heck, I've never heard the term before I saw it on a chart in Costco.

 

[cpacini]

Thanks for the responses folks. I always assumed the tire pressure would differ based on the tire not the car. For what it's worth there was a sticker in the door jam that says 32, so I'll just leave them as is.

 

[RLGL]

Thanks for the responses folks. I always assumed the tire pressure would differ based on the tire not the car. For what it's worth there was a sticker in the door jam that says 32, so I'll just leave them as is.

If this is a car , use the door jamb numbers
Truck inflate to sidewall pressures for heavy loads and use door jamb numbers for normal use.
Engineers figure this stuff out , than know more than I do.

 

[Raizinman]

The door jam sticker and the owners manual do not take into consideration what replacement tire you put on your vehicle. For that matter, the manual and door jam sticker is printed long before the manufacturer knows what tire is going on the vehicle.

Inflate your tires to 25% less than max inflation pressure. Adjust as necessary: Reduce pressure for a smoother ride, or add pressure for longer tire life.

 

[sdifox]

I don't know anyone who buys tires based on load rating. Heck, I've never heard the term before I saw it on a chart in Costco.

Depends on how heavy your vehicle is I guess.

 

[Sulaco]

The door jam sticker and the owners manual do not take into consideration what replacement tire you put on your vehicle. For that matter, the manual and door jam sticker is printed long before the manufacturer knows what tire is going on the vehicle.

Inflate your tires to 25% less than max inflation pressure. Adjust as necessary: Reduce pressure for a smoother ride, or add pressure for longer tire life.

Tires are going to be application and size specific. While they will not "know" what tires are on your car, they will know the size range dimensions (height, width, weight, etc) for the wheel, and therefore, which will necessitate the size of the tire you can safely put on the wheels.

Over inflation is foolish. The contact patch of the tire is reduced, and the tire is more susceptible to damage from potholes and road debris, as well as more "jittery" over uneven or less than perfect surfaces.
Not to mention it can and will make the ride noticeably harsher and more uncomfortable.

 

[pauldun170]

Starting point - Door Jam
Next step - Find other owners with the same car and tire choice and check their experiences with pressure.
Some tires are best left at door jam spec, while others (Like certain continentals with soft sidewalls) like a few extra pounds or wee bit less..

Sidewall spec is based on the tire maximum pressure. This is the pressure the tire manufacturer has decided is the point where they can start calling owners "dumbasses". If the owner exceeds this PSI and the tire fails, the manufacturer can call you a dumbass and void your tire warranty.
If you want to inflate your tires to "tire spec" then go ahead. Just do not mount them on any car. Toss them in your garage and tell people you turned your tires up to "11".

When mounted to an actual vehicle the weight of the vehicle and distribution of weight come into play hence door jam spec.
That label is there for a reason.

If you are to lazy to google, or just too "bro-science" to look at your owners manual then just follow door jam spec.

http://ask.cars.com/2012/03/is-the-...r-on-the-tire-sidewall-or-somewhere-else.html

 

[bruceb]

I go about 3PSI higher than what the car manual or door sticker says. The number they give you is for the softest, most comfortable ride. Some drivers, like me, want a more performance ride and handling which the extra PSI will give you. Do not go above the max sidewall number in any case (this is cold pressure) and do not go way above the suggested numbers. You will know it is wrong when the car becomes skittish or unpredictable in handling and bumps. If it does, back off about 2 or 3 PSI

 

[cpacini]

Starting point - Door Jam
Next step - Find other owners with the same car and tire choice and check their experiences with pressure.
Some tires are best left at door jam spec, while others (Like certain continentals with soft sidewalls) like a few extra pounds or wee bit less..

Sidewall spec is based on the tire maximum pressure. This is the pressure the tire manufacturer has decided is the point where they can start calling owners "dumbasses". If the owner exceeds this PSI and the tire fails, the manufacturer can call you a dumbass and void your tire warranty.
If you want to inflate your tires to "tire spec" then go ahead. Just do not mount them on any car. Toss them in your garage and tell people you turned your tires up to "11".

When mounted to an actual vehicle the weight of the vehicle and distribution of weight come into play hence door jam spec.
That label is there for a reason.

If you are to lazy to google, or just too "bro-science" to look at your owners manual then just follow door jam spec.

http://ask.cars.com/2012/03/is-the-...r-on-the-tire-sidewall-or-somewhere-else.html

See that's the thing, as I said earlier I thought that the correct air pressure depended on the tire, not the car, so I never really considered checking the manual and had never noticed the sticker in the door jam. I did spend some time googling the specific tire I have but couldn't find anything, hence starting the thread. Thanks for the link though.

 

[pauldun170]

See that's the thing, as I said earlier I thought that the correct air pressure depended on the tire, not the car, so I never really considered checking the manual and had never noticed the sticker in the door jam. I did spend some time googling the specific tire I have but couldn't find anything, hence starting the thread. Thanks for the link though.

Stick with the door jam recommendation of 32.
The differences between most common tires are not going to be enough to require major differences in pressure settings for your car.
Would you use the exact tire pressure on a 2500lb car that you would for a 4000lb? No.


Here is decent advise

http://forums.bimmerforums.com/forum/showthread.php?964803-Sumitomo-Tires-Question

1 - If you're running stock rims and suspension, stay with stock pressure or a couple PSI over, not more. If you do go over, watch tire wear at middle of tire.
2 - If you're running stock size, not stock suspension, play with the pressure around stock until you find a pressure that you feel OK with. You may sacrifice tire wear in the end.
3 - If you're running neither stock rims nor suspension, call Sumitomo and ask about the pressure. They may require vehicle weight distribution. Once you get the recommended pressure for your tire/rim size, play around that to to get a comfortable ride with the non-stock suspension.

 

[kitatech]

Running the cushy Camry 20% over doorjamb PSI with OEM-spec tires, the rear wore a bit more in the center, the front a bit more on the shoulders. But with 5k mile cross-rotations, the wear evened out nearly perfectly...I had a good smile on another site where someone questioned whether 1/32" difference between front and rear was anything to worry about...

Now with 17" ultra-performance tires (Ventus V4 ES) in place of 15" OEMs, (both 51psi cold/max inflation), I experience the SAME wear pattern @ 50-40% over doorjamb spec....that's 45 front/42 rear (with about 60lbs extra in the trunk/rear seat)...any less and the tires' shoulders wear a lot more than the center both front and rear, especially so up front....

At this high PSI, their performance is excellent, firming up the soft ride, quickening their response, while maintaining excellent traction on dry and wet pavement under strong acceleration, braking, on curves and at highway speeds in thunderboomers.

What I find odd is that the Camry has a 60/40 f/r weight distribution, leading one to expect that it would require more air up front...which is what I find to be the case even though the doorjamb says 29psi front and rear...

Whether the correct/appropriate PSI is car dependent or tire specific isn't entirely clear-cut to me...In the end I base the PSI on experience, on practical application and experimentation...

 

[SpatiallyAware]

Year make model???????



Love live fleabag :wub:

For a passenger car, truck, I usually go about 15% above doorjamb.

For a performance car with max performance summers I start around 30psi or so if I'm in the mtns or doing track days.


Keep an eye on tire wear when running above doorjamb pressures. Some tires are more sensitive to over/under inflating.

Based on your tire choice you probably have a commuter, so 15% above doorjamb is probably fine.