Safe tire PSI for heavier loads

Higher pressure is better for higher loads. Recommended tire pressure is a function of weight and comfort. Tire safety comes into play when tires are under inflated or inflated above the max pressure rating on the side of the tire.

Tom

 

First, what Tom said. Second, max sidewall pressure is not "hyper inflated". This sounds like a good Mythbusters question. "How high does the psi have to be for a tire to blow?"

 

most passenger cars with 60 to 65 series tires recommend 35 psi, most tires for these vehicles say the max is 42 to 45 psi, but i'm sure they're safe to 50psi, but its not worth a blowout.

I typically put 35psi up front, and in the rear I put 30 in back because I don't carry any heavy loads, but you may just want to put 35 all the way around.

some people on this site like to put 40 to 45 psi in the winter time, this increases the mileage by having less tire surface touch the ground and results in less road resistance, but this also results in less traction in the snow and ice, getting a few extra mpg is not worth your life, and certainly not worth your family's life.

I've got heavy steel wheels and snow tires on so I'm getting even worse mileage than you. Just live with it, its only a few months out of the year, and the 40mpg I get in the winter is still better than 99.99% of the cars out there. The rest of the year I get over 50mpg which is better than 100% of other cars.

 

By law the Maximum safe cold air pressure is marked on the sidewall of every tire. The OE Goodyear Integrity tires on the standard 2004+ Prius are rated safe to 44 PSI. My second set of tires were Michelin MXV4+ and were also rated safe to 44 PSI. My new Nokian WR tires are rated safe to 51 PSI.

Stay below the rated maximum for your tires and then you don't have to worry.

JeffD

 

Tire rack has a pretty good article on air pressure related to speed and max loads. Take a look:

Tire Tech - Air Pressure/Load Adjustment for High Speed Driving

 

There is a similar article on a Bridgestone truck tire site:

Bridgestone Commercial Truck Tires

The article explains why load rating is higher with higher air pressure (heavy loads make sidewall flex when tire rolls and limits the load, higher inflation pressure makes the sidewall flex less).

 

For any load, speed, and driving condition you can use your tire pressure guage to find the best choice. Compare cold (before driving) tire pressures to those measured hot, after you have been on the road for a while. The measured increase in pressure should not be more than about 10%. If >10%, then a higher starting (cold) inflation is appropriate. Some experimentation may be required.

If you cannot get down to a 10% increase 100*(H-C)/C, then your tires are not appropriate for your load, speed, and driving condition. Remove weight or slow down, etc.