tire psi question

[Rapid Robert]

a month ago a tech at one shop said the small cast load/psi numbers on the side are for max load & for normal useage go several pounds above that. another shop fixed the spare on my van a few days ago & the same small print says 60 lbs but they said to keep it at 40 psi. whats going on? your thoughts please. RR

 

[MV8]

All tires leak over time. I usually put 40 psi in everything because I am lazy. If you wear the center tread thin first, then the pressure is too much. I'd never run max. Too little and the outside edges wear faster than the center and the tire can slip on the rim.

Cars that are super light but have big tires need lower pressure to wear even. Tire temps can be checked across the tread with a tire pyrometer after a run. Even heat is what you want. A hotter tire is only better for traction up to a point.

 

[Professor Fate]

Use the vehicle's recommended pressure.
Max PSI is just that- the maximum pressure the tire is designed to safely work at.
Recommended pressure is completely different. Since the same tire can be used on many completely different vehicles, the recommended pressure can vary in each application dependent on vehicle weight and individual tire loading- this is why you may find different pressures listed for front/rear tires. It's all about getting an even contact patch between the tire tread and the road, thus promoting even tire wear. This is also why proper pressure can and will change if you switch to non- stock tire sizes.

 

[496 polara]

The tire information sticker in the drivers door jamb area (usually) is the recommended normal cold (a tire not driven on recently) air pressure. You can generally plus or minus 3lbs depending on your driving style and whether or not you want a softer or firmer ride.

The max pressure on the sidewall is how much weight the tire can hold at that pressure. So unless you are travelling with a couple of cast members from my 600lb life you shouldn't be anywhere near max pressure. Now throw 4 adults and luggage in the car and you may want to add some air to the normal pressure to compensate.

The donut or space saver spare tires usually call for 60 psi and I would run every bit of that in them. You are supporting a car with a motorcycle size tire should you have to use it. A regular size spare I usually throw at least 40psi in them as you never know how long it will sit before you actually use it and most people don't check them periodically.

 

[YY1]

What car wants 60?

My 2015 Renegade calls for 35.

 

[Rapid Robert]

excellent info, I'll get on it! thanks guys. RR

 

[496 polara]

What car wants 60?

My 2015 Renegade calls for 35.

The donut spare tires typically do.

 

[Dana67Dart]

A side note....

Our A bodies pressure numbers were designed for narrow bias ply tires you have to exparement.

I have seen people use carbon paper or chalk to see where the tires are riding.

As mentioned too much pressure and the darkest areas will be in the center of the tire. Too little and the center will be lighter.

 

[jbc426]

If you're running a correctly matched rim size, you can find the tire pressure your combo wants in order to have a full contact patch by using chalk.

Scruff about an inch wide mark of some chalk across the tread from inside to outside on the tire. Drive in a straight line for about 40 feet, and see how the chalk has worn across the tread. If only the middle, then lower pressure and repeat. If only on the outside edges, then add air. If only +- 75% or 80% of the tread including the middle, reduce air pressure until it wears evenly across the tread. The maximum pressure recommended on the side of the tire is

It's all about the shape of the tire's bulge on the ground contact given the weight that's currently on a given tire.

Keep this in mind too. I run 18psi on my Nitto 275/60-15's for maximum contact patch i.e traction, however I increase the pressure up to 22 psi for road trips to account for the car being heavier (still full contact patch), and to allow the sidewalls to be stiffer for cornering.

Same thing for my 3/4 ton truck. With nothing in the bed, the rear tires like 42 psi, while the fronts like 45 psi. with 500 pounds in the bed, the rears need 45 too. The tires wear extremely evenly when I adjust their pressures this way.

Almost everyone uses too high of tire pressure when going by what the sidewall pressure recommends at maximum load, because their car puts no where near that weight on their tires. Their tires wear out in the middle in most cases. In my case, my truck tires sidewall reads 80 psi for 3970 lbs load max. The entire truck only weighs 7500 lbs. unloaded, and ready to travel.

 

[33IMP]

Uh, several pounds ABOVE max on the tire? Nope.
Pressure depends on tire, and usage.
Tires on the back of my Opel run 15lbs or so. Less at the track.
My sporty car 20s get 40 or so, on a 44 lb maximum.
My truck tires with 75lb max normally run at 55, bumped to 70 when towing
My trailer runs at full max pressure, cold
My box truck 19.5s run at 100lb.

I'd run your tires at around 5lb under the stated max to start, then adjust for proper wear, and preferred ride.

 

[33IMP]

What car wants 60?

My 2015 Renegade calls for 35.

He mentioned a van.
Depending on the load rating on the tire (E?) lots of light truck tires can be run at 60 lbs
Max on my pickup tires is 75, on my box truck, 120lb.

 

[Kendog 170]

35 PSI on my Darts. Street diven.

 

[AJ/FormS]

28psi in the 235/60-14 fronts, and
24psi in the 295/50-15 rears, gets my tires flat to the road and that is where I get the maximum treadwear and grip, out of the treads.
I throw my tires away NOT because they are worn out, but because the bottom half of the treads have no grip left...... When my rear tires start to spin in third gear, well, it's long past due, and when the front starts skating around, they gotta go.
I used to put them on something else on my yard, but I ain't that poor anymore, nor do I have anything left to install 295s on anymore.

 

[Rapid Robert]

right now the van has 50 on the fronts/35 on the rears. I had a flat & thats when I saw the 65 on the spare & that seemed high and just today I just noticed it said (65 single/65 dual axle.) I guess that explains the very high 65, its not a normal tire. thanks a bunch guys! RR

 

[Dana67Dart]

right now the van has 50 on the fronts/35 on the rears. I had a flat & thats when I saw the 65 on the spare & that seemed high and just today I just noticed it said (65 single/65 dual axle.) I guess that explains the very high 65, its not a normal tire. thanks a bunch guys! RR

What tires do you have on your van?

what's the max pressure on the sidewall of each tire?

is your spare a full size or space saver?

Real truck tires typically require higher pressure than passenger car tires

 

[Darter6]

What car wants 60?

None that I know of. I have seen new tires that state 44 psi on the side wall.

 

[YY1]

Higher PSI gets you a bit more MPG.

I'm currently running mine at 38.

Might wear the center a little more.

Not on the last set I just took off, but those were run about 36.

 

[Dana67Dart]

If you drive a lot the cost of prewarn tires might not offset the savings in gas.

Not driven much (replace every 7-10 years regardless of milage and wear) and you might save a buck or two. But... Tire grip to the road will be less with a smaller contact patch.

 

[YY1]

You'll be super lucky to get 7 years out of todays tire compounds.

I've had 4 year old tires bust their belts sitting in storage.

 

[DartGTDan]

I just looked up my tires (Mastercraft Avenger G/T) online and the specification states 44psi. If I remember correctly, I have them set at 36psi. Maybe I'll try the 44psi (if we ever get spring/summer weather).

 

[Dana67Dart]

You'll be super lucky to get 7 years out of todays tire compounds

I'm on year 9 on my Cooper Cobras. I'll replace them in 27. I think I rotated the tires 1 time.

About 1000 miles per year, so only about 9-11,000 miles on the tires

 

[crackedback]

Chalk works well. If you do chalk test, try it with the tire hot at driving temps. Tire pressures increase with heat.

Note cold temp pressure, get them up to temp. Chalk and observe. Same approach as described. Inner wear, air out, outer add air. Take hot pressure reading, make adjustments. Add subtract adjustments to the cold pressure and you'll likely be close enough.

 

[33IMP]

You'll be super lucky to get 7 years out of todays tire compounds.

I've had 4 year old tires bust their belts sitting in storage.

I recently replaced the rears on my SS Camaro, they were getting thin, and were definitely old. I bought new for the front too, but I'm trying to get some more mileage out of the oem fronts (Pirelli P-Zero, factory issue on a 2012, still look and drive perfect. )

 

[MOPAROFFICIAL]

41 to 44 psi is fine for most tires that say max 51psi

 

[RustyRatRod]

I always start out at the max pressure listed on the sidewall and drop down from there IF the ride quality is a little harsh. The listed specs for the vehicle is all about ride quality. That's why they appear to be "low" like 28-32 PSI. If you want the longest life out of the tires, you should run higher than that. That's why I normally run whatever the max is and let my suspension do its job.