My back tires are bald in the centers which tells me overinflation which I do run 60-70psi in all the time, loaded or not. I know Mike has that calculator but I am not convinced it works seeing as how no load would mean no pressure. The front tires are bald on the insides, which tells me the springs are shot, which I'm sure they are lol. Airbags for the front was only $80 so I will get the front jacked up to fix that issue.However, how do you know where level is? If I jack the front up, how do I know when the tires are perfectly flat on the ground, not leaning to one side or the other? This should factor in tire pressure probably since more pressure will make the center of the tire protrude more than the rest of the tire.I am not looking for any guesswork, I want dead nuts accuracy on this issue. I have some theories on what to do but most of you have more experience than me so I'd like to hear what you guys have to offer.

i run 50 psi on my superswampers and i dont load anytyhing. they are as flat as pancakes as far as wearing. i hear of people running the fronts higher since the boat anchor is up there.

Yeah even my tire calc. turn out highier pressures on the front axle than rear axle. So you need to bring down the rear tire pressure. As for the front axle its a mater of find out what stock measurements are for that model. I would contact a local body shop of measure they should have them.

i run about 60psi all the way around when not hauling the rv. rotate about every 5,000 or at least every oil change, about 8,000. they seem to wear pretty good like that for me. the only time i had issues was when the froont was worn out. really had uneven wear then.

I found if you google load and inflation tables, you find a ton of info. Might do the chalk thing to see what that yields. Those airbags were uh, interesting. Says smash all the air out then plug them, then cram them through the spring coil with a "blunt NOT SHARP, object". Well 10 min later I had one in, being nice to it and using the end of a hammer as a blunt object. By the time I was done, I decided anger was a perfect replacement for "blunt object". I scraped the blunt object and went at the other side with full fury and had it in in a minute

ISX, A few drag racers I've been around would run some chalk (like from a chalkline) across their tires, then roll it forward on clean black pavement and see where the chalk sticks. Some of the others would chirp their tires, and see if the tire imprint was square. Even with the 12V you should be able to spin the tires with the NV4500 . They would adjust their pressures accordingly.

CSM gives the right method. Check your contact patch. Once you have uneven wear it's a little late. Over-inflate, drop pressure gradually until you have solid contact on the shoulders, and 2-4psi lower than that is your best pressure for optimal tread wear. As for shoulder wear, why do you think it has to do with ride height and not toe? And you must have an IFS 4x2 if ride height can effect camber... Just get it aligned. If its a solid front axle, toe is all that's adjustable and you can do that with a tape measure. Should be toed in about 1/4". Jack up the front, mark each tire an measure between the marks. Spin the marks to the back of the tires and remeasure. Should be 1/4" closer together in front.

  mr.mindless said:

CSM gives the right method. Check your contact patch. Once you have uneven wear it's a little late. Over-inflate, drop pressure gradually until you have solid contact on the shoulders, and 2-4psi lower than that is your best pressure for optimal tread wear. As for shoulder wear, why do you think it has to do with ride height and not toe? And you must have an IFS 4x2 if ride height can effect camber... Just get it aligned. If its a solid front axle, toe is all that's adjustable and you can do that with a tape measure. Should be toed in about 1/4". Jack up the front, mark each tire an measure between the marks. Spin the marks to the back of the tires and remeasure. Should be 1/4" closer together in front.

I am not a tire expert by any means. In my mind if the truck is sagging at the front, which yes it is IFS 2wd..then that would make the tires taper in and ride on the insides of the tires, that are bald. I would have thought toe would do something else so do tell why it would be a toe issue.

I'm not used to having adjustable camber with solid front axles in everything I play with alignments on, so in my world toe out wears the insides and toe in wears the outsides, and that's that...

  mr.mindless said:

I'm not used to having adjustable camber with solid front axles in everything I play with alignments on, so in my world toe out wears the insides and toe in wears the outsides, and that's that...

I've always looked at it as tires are flexible, and when you are toed out, the insides of the tires are what is going to be rubbing the most as the rubber flexes. The tires will pull the inside edge under to make the inside of the tires rub on the road more. As for what effect the camber/caster has on the tires, I am not sure. Also, I was just kidding about your 12v above fyi. ;)

  CSM said:

I've always looked at it as tires are flexible, and when you are toed out, the insides of the tires are what is going to be rubbing the most as the rubber flexes. The tires will pull the inside edge under to make the inside of the tires rub on the road more. As for what effect the camber/caster has on the tires, I am not sure. Also, I was just kidding about your 12v above fyi. ;)

Guess I need to stare at my truck to see what the underlying issue is. And I know, chirping them is in understatement though I can light them up in 4th at 45mph on dry pavement or 5th at 55 in the rain

The rear needs less pressure and the front needs an alignment. If you can't align to OEM spec's then look at suspension parts. The tire pressure chart works! 0 load is 0 psi, but 0 load is tire off the truck, or ground. Here is a good article from Toyo, and should apply to any tire with the same size/load rating/psi. [ATTACH]3310[/ATTACH]

Inflation_Tables_2012.pdf

  AH64ID said:

The rear needs less pressure and the front needs an alignment. If you can't align to OEM spec's then look at suspension parts. The tire pressure chart works! 0 load is 0 psi, but 0 load is tire off the truck, or ground. Here is a good article from Toyo, and should apply to any tire with the same size/load rating/psi. [ATTACH]3310[/ATTACH]

That table is what I found and why I linked to the google search so you could see all the other tables. Alright I messed up the first time. Mike's weights are different from the chart as in at 35psi by weight on the chart, his thing says 45. Seems to get closer as weight gets closer to rated.

Like looking at that inflation table is the max inflation at max load... So lets say like my rear axle... With a load range E's (3042# @ 80 PSI) and max axle weight (6084#)...6084 / 2 = 3042# pounds per tire.3042 / 3042 = 1.00 Or a 100% of the tire rated load.1.00 x 80 = 80 PSI which is the inflation pressure.But we know you truck rear axle weight isn't exactly at 100% GAWR... So since you not at max load you at a percentage of load... So like my rear load weight with the trailer hitched up is 4,280...So since rear axle has half the weight on each tire you divide by 2...4,280 / 2 = 2,140 pounds of weight on each tire. Which each tire is rated for 3,042 pounds as the tire guide shows. So now divide 2,140 pound actual weight over 3,042 tire max capacity weight.2,140 / 3,042 = 0.70 So the tire is at 70% of its load capacity. So would it logical be right to inflate the tires to about 70% of the air pressure?So if the tire max air pressure is 80 PSI that means multiplying 80 times .70 would net you the pressure?0.70 x 80 = 56 PSI... Me... Then I tend to just round up to the next full tens of 60 PSI so that would be my inflation pressure for my rear axle. Remember never to exceed the tire rated pressure!Now using one from the table...2765# / 3042# = 0.90 x 80 PSI = 72 PSI (Table rates it for 70 PSI at that weight) so I'm not too far off! :tongue:1870# / 3042# = 0.61 x 80 PSI = 49 PSI (Table rates it for 40 PSI at the weight) I'm looking better with my number...

Whoops, missed your link. I have found that 40 psi in the rear is good for me when empty, and the chart doesn't even go that low (1,600 per tire), but 1,945 per tire is 40 psi. Mike's chart would be 40 as well.For the front I run 55(winter)/60 (summer) as a minimum for stability, and that's at 2,400 lbs per tire. The chart says 55, and Mike says 60. I didn't use a chart to determine my pressures, I used feel and wear.. I think that validates both charts as accurate. Remember a tire psi chart is a starting point, not a hard number. Now towing I run 75/75 at 5,000 and 5,000 or close to. Toyo says 60/60, Mike says 63/63.. I like the stability, tire time, and wear of more air. The Toyo chart does use slightly different pressures, up to max load/psi, for different tire sizes but not much. I run either a 255/80/17 (surprised it was on the Toyo chart as the only tire in that size is a BFG) or a 265/70/17. They are both rated for 3195 @ 80 psi.

I made an intricate setup to measure if there was any misalignments in toe or whatever my theory is, camber? Anyhow, toe was perfect. Could not find anything misaligned there. I used calipers to do all my measuring so I kinda doubt I wasn't accurate enough.. Then came camber, it was actually the opposite of my theory, as in the tops of the tires are farther apart than the bottoms, so they are leaning outwards, but this was hardly even measurable, it also says the outside of the tires should have been wearing, not the insides. However, the testing was done with the back tires on the front so they aren't bald on the inside like the others were, and this was with the air bags in front with lots of pressure. So either the air bags did it or the tires did it, or both. I'll do further testing if I notice these tires are wearing on the inside as well, from what I saw they hadn't done so yet.

just pull the engine and you can measure them.:lmao2:the only time i got uneven wear was before i rebuilt the front end. they wore off on the outside and the inside like they were under inflated. when i noticed it i started running 80 psi all around to no avail. i know once you have the uneven wear theres not much you can do about it, but i figured the 80 psi unloaded would of helped more than it did. put a new set of tires on after the rebuild and they are wearing evenly. iam runnig 60 unloaded and 75 to 80 pulling the 5th wheel.

Different rim widths will affect contact patch too. Any chart is an educated guess at best. Chalk test is the way to go. What's "perfect toe"? If your toe is 0, you are toed out beyond spec and should expect a slightly off-center or darty steering and mild inner wear. Not as much as actually being toed out, but a rwd vehicle should be toed in slightly.

  mr.mindless said:

Different rim widths will affect contact patch too. Any chart is an educated guess at best. Chalk test is the way to go. What's "perfect toe"? If your toe is 0, you are toed out beyond spec and should expect a slightly off-center or darty steering and mild inner wear. Not as much as actually being toed out, but a rwd vehicle should be toed in slightly.

I didn't do it the way you are supposed to as I have no clue how you are supposed to do it. I did it a different way, comparing the straightness of the front tires to the straightness of the back tires. I measured off the wheel not the tire, making one side as straight as possible in relation to the back tire by turning the steering wheel, once that side was perfectly aligned, I went to the other side and didn't touch the steering wheel and saw how far off it was, which it was perfectly aligned as well. I used a longg "straight edge" to do this. Might not be how you are supposed to check toe but I don't see how it wouldn't work. Hmm, just read some other ways of doing it so maybe I'll try them as well.

I outlined the Tape measure toe method earlier in the thread:

  mr.mindless said:

Should be toed in about 1/4". Jack up the front, mark each tire and measure between the marks. Spin the marks to the back of the tires and remeasure. Should be 1/4" closer together in front.

Again, if your tires are perfectly straight, you're toed out slightly further than you should be.

Sounds like you need a front end alignment