Already have a pro cal and I plan on using it before I leave the tire shop but what air pressure should I run for the 5 hr trip back to my home since I am down visiting family the tires are Toyo mts. And the tires aren't true 35s they are the 315s. And is there any big size difference between the two

 

Depends on load range of tire and actual diameter. I have 35" Toyo Open Country MTs (load range E. measures 34.75) and I run 32lbs but the tire actually calls for 65lbs. Running 32lbs gives a nice ride.

 

I run 32 as well but I have seen people say they go as low as 26-28.

 

Take a tape measure and GPS with you. The procal is very easy to use thankfully, so adjustments to tire size are easy. Actually any program is easy. Bring a tooth pick or something to get the little switches easier.

Bring a tape measure to get an exact diameter for your calculation for the procal programming. Don't go off of any diagrams, manufacturer's stated size, etc. Fill the tires to your specifications (I think way of life has a sticky on tire pressures), measure from there. Then make adjustments by comparing your speedometer to your GPS if you have one. I highly recommend you borrow one if you don't have one. I used one on my turn by turn app on my iphone (I don't think the google maps one has speed). Any ways, I adjusted my programming after comparing it to what the GPS told me. Another option is to use one of those stationary radar things that encourage you to not speed if you know where one is.

Enjoy. Also start thinking about if you are going to mix your spare tire into the rotation. I bought my tires used, and they already had 9k miles on them with none on the spare. If I bought them new I would consider rotating in the spare, because you don't know if you are going to buy the same brand tires or not, etc etc.

 

Keep in mind, that the pressure stated on the sidewall of the tire is the MAXIMUM presuure the maufacturer of the tire guarantees it will hold before removing whatever corner it is mounted to.

Alot of the bigger mud terrains are between 6 and 10 ply, ranging from 65-85 psi.

The larger the tire, the more surface area you have contacting the ground, which is more surface area for pressure in the tire to hold the vehicle up.

Basically, the bigger the tire, the less air you actually need. Best way to test is the chalk test, but I run 30psi in my 35's

You should be fine right there.

 

Are we talking about 315/70/18's or 315/75/16's? I'm running 315/75/16's at 26psi.

 

315/75/16. And thanks for all the info I will tell them to put it at 32 to see how it is for the 2 hour ride back to my moms house and make adjustments from there. My uncle runs the tire shop so I can be picky and help out to make sure. I like to be as hands on as possible.

 

If you have a 2 door like me I run 28 after doing the chalk test has the best even wear pattern and a nice smooth ride. If you have a four door 30-32 upfront 32-34 in the rear. Also toyo m/ts pull to the right don't freak out after your alignment that its still pulling. Good luck

 

Great. Thanks for that info