Hey everyone. Got some Hankook Optimo H727s put on the truck. And the guys in the shop screwed up. They only put in 33 PSI in and the tires are squating. The max pressure is 50PSI. I typically have ran tires right at or just under the max psi stated on the tire. What pressure do you guys recommend?

The max pressure has almost nothing to do with what you are supposed to put in the tire. The max pressure number is what the manufacturer of the tire states that tire can hold before it blows out. Since the tire manufacturer has no idea what kind of vehicle the tire is going to go on, thats the only number they can provide to make sure their tire doesn't fail.

Basically, a tire has a specific footprint required to keep an even distribution of weight across the whole tread. That footprint is a surface area in square inches. Your truck has a specific curb weight to it in pounds. The psi... pounds per square inch... that you should put in your tires should correspond with the weight of your truck and desired footprint of the tire. In your door jamb is the manufacture's specified air pressure... they already did the math. If you are using a bigger tire, it has a bigger footprint and therefore does not need as much air pressure. If you are using a smaller tire, it has a smaller footprint and therefore needs more air pressure.

The only way to know for sure what pressure to use in a non-factory size tire is to weigh your truck and measure the desired footprint of the tire and do that math... but that is tedious work and has too much room for error. The best thing to do is guess. If the new tire is bigger, go down 1 or 2 psi and if its smaller, go up 1 or 2 psi from the factory recommendation.

I took my truck into the same firestone shop last week. Last week they put 35 psi in my goodyear radials and today put in 33.5 in the hankooks. Both tires are the exact same size as what the truck originally came with. I know this as I had chrysler send me the build sheet based off of my vin. I guess I may as well start at 35 psi for now and see about contacting hankook for what they recommend I use.

I highly doubt they will have a recomendation. Like I said before, it all depends on how heavy your truck is as to how much air you should put in the tires.

If you have factory size tires, then definately put in 35 psi.

its all about 'contact patch' if you're running the street i would run the tire at 45 cpsi. snow 35 cpsi. sand 25 cpsi. if you're towing or have a heavy load run it at 50 cpsi. the number in the door is for the stock size tire.

Um, no. If you run at 45 psi on the road and the truck calls for 35, you'll have too small of a footprint (contact patch) and you'll wear the tread unevenly... the middle will wear out fast.

Its very simple... if the truck says 35 in the door jamb and you are running a factory tire, run 35 psi!!!!!! The engineers who designed the truck already did the math and determined that 35 was ideal for that size tire.

If you want to know how much air to add for towing heavy loads, go and actually measure the footprint of the tire with the correct pressure and truck empty (at curb weight), determine how much weight you are adding to the truck, and do the math for how much air to add. And you'll only want to add that much air to the rear tires, since the weight over the front will change negligably.

And just keep in mind, with the way tires are designed, there is room for error of + or - 1-2 psi with no ill effects on treadwear.

Just got this in from Hankook Tires Tech department:

Juan A. Britos to me
show details 10:04 AM (45 minutes ago)


It looks like 35 psi is a good level to put the tires at for everyday driving.

Best regards,

Juan A. Britos
Assistant Manager
Technical & Service Team
Hankook Tire America
1450 Valley Road, Wayne, NJ 07087
(973) 406-3614
(973) 633-9980 fax