Psi question
10-31-2010, 07:31 PM
#1
JK Newbie
Thread Starter
Join Date: Apr 2009
Location: Las Vegas, Nevada
Posts: 86
Likes: 0
Received 0 Likes
on
0 Posts
Psi question
I just had a lift and new tires and wheels installed. I'm running 33" Toyo MT's. Psi rating is 65 and I believe that's what the shop filled them up to. What should I really be running them at? Opinions? Advantages and disadvantages to a lower psi?
11-01-2010, 08:56 AM
#2
JK Super Freak
I didn't use a formula, just estimated based on experience and 28 is what I run in my 35x12.5 and they are wearing just right. So I would have to agree with what the formula says. I will have to copy that formula down for future reference. Get something good off this forum almost everyday, thanks.
11-01-2010, 09:05 AM
#3
JK Freak
Join Date: Jun 2008
Location: St. Peters, MO
Posts: 653
Likes: 0
Received 0 Likes
on
0 Posts
Your 2 door with stock bumpers probably weighs around 4100 lbs with you in it.
If you are running the LT305/70R16 Toyo MT, it has a max load rating of 3525 lbs at 65 psi. (4 x 3,525 lbs = 14,100 lbs max load at 65 psi)
The tire was designed to be run on a full size truck.
The formula to find the starting point for the appropriate psi for you might be:
4100 lbs * 35% = 1435 lbs
1435 lbs / 3525 lbs = 41% of max load
65 psi * 41% = 27 psi
So, for you to get a flat tread wear pattern, you probably need to start at 27 psi and do a chalk test.
Without a flat tread wear patter, you will ruin your tires because you will be riding on the center section and the tire will not last as long.
If you add 300 lbs of gear and armor, that only increases the result to 28 psi.
For extended freeway driving in the summer, you might increase this by 3-5 psi if your tires get hot.
Here is an article on the chalk test:
h ttp://www.moabjeeper.com/articles/general/listing.cfm?articleID=492
If you are running the LT305/70R16 Toyo MT, it has a max load rating of 3525 lbs at 65 psi. (4 x 3,525 lbs = 14,100 lbs max load at 65 psi)
The tire was designed to be run on a full size truck.
The formula to find the starting point for the appropriate psi for you might be:
4100 lbs * 35% = 1435 lbs
1435 lbs / 3525 lbs = 41% of max load
65 psi * 41% = 27 psi
So, for you to get a flat tread wear pattern, you probably need to start at 27 psi and do a chalk test.
Without a flat tread wear patter, you will ruin your tires because you will be riding on the center section and the tire will not last as long.
If you add 300 lbs of gear and armor, that only increases the result to 28 psi.
For extended freeway driving in the summer, you might increase this by 3-5 psi if your tires get hot.
Here is an article on the chalk test:
h ttp://www.moabjeeper.com/articles/general/listing.cfm?articleID=492
11-01-2010, 09:10 AM
#4
JK Junkie
Join Date: Apr 2007
Location: Apple Valley, California Good ole Mojave Desert.
Posts: 3,695
Likes: 0
Received 0 Likes
on
0 Posts
i run my 35 toyo's on the road at 28psi. good ride even wear
get those suckers aired down to around 30psi and take it for a drive you will notice a big difference in the ride.
get those suckers aired down to around 30psi and take it for a drive you will notice a big difference in the ride.