Setting tire pressure based on load and inflation tables?
12-17-2012, 06:49 AM
#1
JK Super Freak
Thread Starter
Setting tire pressure based on load and inflation tables?
Ran some searches, didn't see any hits..
Anyone have an experience or input regarding setting your tire pressure based off of load inflation tables for your tires?
This is strictly in regards to running non-stock tires.
Theory is, you compare your stock tire load rating (at factory recommended pressure), to the new tires load rating inflation table. You find closest load rating at or above the stock rating, and run the referenced PSI.
I'm seeing conflicting info regarding this method.
Anyone have an experience or input regarding setting your tire pressure based off of load inflation tables for your tires?
This is strictly in regards to running non-stock tires.
Theory is, you compare your stock tire load rating (at factory recommended pressure), to the new tires load rating inflation table. You find closest load rating at or above the stock rating, and run the referenced PSI.
I'm seeing conflicting info regarding this method.
12-17-2012, 06:52 AM
#2
JK Freak
Most of us I have found use the good ol chalk line method. Shows accurate wear pattern on the tire based on how the vehicle sits. This takes out all the guessing and keeps it simple and perfect.
12-17-2012, 08:05 AM
#4
JK Super Freak
Thread Starter
My concern with the chalk test is that I've already got about 15k miles on my tires, and I am assuming they have worn in to the pressure I've been running.
I also like the hard numbers involved with the inflation tables...
I also like the hard numbers involved with the inflation tables...
12-17-2012, 08:13 AM
#5
JK Enthusiast
Inflation tables would differ to much between tire types. This is why when someone posts they want to know what psi to have their 35s at you get 20 different answers.
Technically you could create on for each tire type and size but it still would only be a reference chart and should be checked manually.
What I still don't understand is the amount of people that think higher PSI will make their tires last longer..
Technically you could create on for each tire type and size but it still would only be a reference chart and should be checked manually.
What I still don't understand is the amount of people that think higher PSI will make their tires last longer..
12-17-2012, 08:16 AM
#6
JK Super Freak
Thread Starter
Looking up my stock and current tire sizes and loads... here's my figures:
Stock: P255/70-18 - 112 load index -- 2469 @ 44psi.
New: P265/70-18 - 114 load index -- 2601 @ 44psi.
Stock pressure is 35psi.
(Note: load capability maxes out at 35psi for each of my tire types. The load specs above might as well each say @ 35psi).
Using the tables, to carry the same 2469 load the new tires require 31psi of pressure. That seems low for a 265 tire.
Not sure if this method really works out or not....
Stock: P255/70-18 - 112 load index -- 2469 @ 44psi.
New: P265/70-18 - 114 load index -- 2601 @ 44psi.
Stock pressure is 35psi.
(Note: load capability maxes out at 35psi for each of my tire types. The load specs above might as well each say @ 35psi).
Using the tables, to carry the same 2469 load the new tires require 31psi of pressure. That seems low for a 265 tire.
Not sure if this method really works out or not....
12-18-2012, 06:37 AM
#7
JK Super Freak
Thread Starter
Just following up.
Dug into this some more yesterday.
Seems like using the charts to find correct tire pressures may only be suited for when you go from a P-metric to LT, or LT to floatation - and you need to run increased pressure over stock.
Tire manufacturers and the tire charts don't recommend running any pressure lower than than what the manufacturer originally called for. Even for oversized tires. But based on info I hear on the board and elsewhere, I wanted to experiment to see if I could dial my Jeep in better.
I ran my tires at 32psi yesterday. 32psi on my new tires is still about 100lbs/tire better load capacity than stock tires. The tires 'looked' ok, and the jeep rode nice and compliant - but the tires were squirmy, grabbed at inconsistencies in the road and were not very sure footed. The Jeep almost felt dangerous at highway speeds. The tires only picked up a 2psi increase in pressure over a 25 mile drive - which is in spec, but 32psi was still obviously the wrong cold pressure to start with. Not recommended at all.
So this morning I aired the tires right up to 35psi (door recommended pressure), and it's a night and day difference. I am back to feeling every bump in the road, but the Jeep handles and rolls so much better.
I still cant help but think my best setting is somewhere around 34-34.5 psi (which is what I normally aim for), but it was nice to walk through things and try it out.
Dug into this some more yesterday.
Seems like using the charts to find correct tire pressures may only be suited for when you go from a P-metric to LT, or LT to floatation - and you need to run increased pressure over stock.
Tire manufacturers and the tire charts don't recommend running any pressure lower than than what the manufacturer originally called for. Even for oversized tires. But based on info I hear on the board and elsewhere, I wanted to experiment to see if I could dial my Jeep in better.
I ran my tires at 32psi yesterday. 32psi on my new tires is still about 100lbs/tire better load capacity than stock tires. The tires 'looked' ok, and the jeep rode nice and compliant - but the tires were squirmy, grabbed at inconsistencies in the road and were not very sure footed. The Jeep almost felt dangerous at highway speeds. The tires only picked up a 2psi increase in pressure over a 25 mile drive - which is in spec, but 32psi was still obviously the wrong cold pressure to start with. Not recommended at all.
So this morning I aired the tires right up to 35psi (door recommended pressure), and it's a night and day difference. I am back to feeling every bump in the road, but the Jeep handles and rolls so much better.
I still cant help but think my best setting is somewhere around 34-34.5 psi (which is what I normally aim for), but it was nice to walk through things and try it out.