Yeah, if you get squirrelly tires, it hurts your handling.

You could widen the search by considering other tire sizes though, such as 31 x 10.5/15 or 32 x 11.5/15, etc.

 

Yeah, if you get squirrelly tires, it hurts your handling.

You could widen the search by considering other tire sizes though, such as 31 x 10.5/15 or 32 x 11.5/15, etc.

LOL, is it the tire type or the size? I know the OE tires sucks but I'd figure the taller/wider/heaiver 31 & 32s would slow steering response some.

 

Sometimes a different tire takes a different PSI to work with a particular weight rig, etc.

Sometimes AT tires just don't handle as precisely as hwy tires, and, MT's not a well as AT's, and so forth.

Some tires are designed to ride soft, as the target buyer want it smooth, and that's the only adjective for a tire or ride description they know....and not to handle like the rig is on rails.

 

LOL, is it the tire type or the size? I know the OE tires sucks but I'd figure the taller/wider/heaiver 31 & 32s would slow steering response some.

I think more of it has to do with the load rating, pressure, and sidewall construction/size of the tire.

My work truck ('05 Colorado) handles pretty poorly with standard load 265/75/15 highway tires on it, but it handles nicely with a set of 31x10.50R15LT 6ply All Terrains. The difference is in the load rating. the 6ply LT tire is stronger and runs at a slightly higher pressure.

My current thoughts on my Xterra is to go up to a 17" Wheel with a LT265/65/R17 BFG AT KO or KO2 which is 8ply or load range E. Not only will that be a stronger tire, but it will also have less sidewall due to the bigger wheel. Most of the reviews I hear for the BFG's are all positive.

The X also needs new shocks, at least on the back. My 2-year old Bilsteins with barely any use are SHOT... The X mostly sits these days because I work all the time and when I am working I'm in my Colorado. I'm confused as to how the Bilsteins are bad so quickly with such little use.

I'm getting ready to start working on the X again, so I will have more to update as I change/fix things...

 

What about a rear sway bar?

And are your tires overfilled? Alot of places will overfill your tire so they wear out fast and you'll always be replacing them..

Make sure the PSI is only what's written on your door

 

My first guess would be out of balance tires or control arm bushings, although for the rig to be a "handful", those bushings would be in pretty obvious bad shape. Those long trail TA's are good tires, and balanced correctly with proper inflation, they should not be the source of the problem. Especially in OE size.

 

What about a rear sway bar?

And are your tires overfilled? Alot of places will overfill your tire so they wear out fast and you'll always be replacing them..

Make sure the PSI is only what's written on your door

NO!!!!

What's on the door placard is ONLY (ONLY) applicable to a stock X with the OEM tires.

If you buy the same size but a different tire, etc...the PSI you want might be different.

 

But how would you go about figuring out the proper amount for a given tire, as the vehicles they're on are all different, different weights, different payloads, and probably other factors like BS or Suslift may come into play..

Most places actually overfill the tires, and will even tell you they're doing it for this or that reason, but the main reason is actually for increased wear and decreased life.

Max PSI rating is the maximum level it can be safely filled to, not the optimum pressure.. And a stamp on the tire wouldn't help for various vehicles, loads, and surfaces

 

But how would you go about figuring out the proper amount for a given tire, as the vehicles they're on are all different, different weights, different payloads, and probably other factors like BS or Suslift may come into play..

Most places actually overfill the tires, and will even tell you they're doing it for this or that reason, but the main reason is actually for increased wear and decreased life.

Max PSI rating is the maximum level it can be safely filled to, not the optimum pressure.. And a stamp on the tire wouldn't help for various vehicles, loads, and surfaces

A good question.

The STARTING point is to take the max load rating and max psi from the sidewall and get your GVWR, or, weight of your rig when loaded as much as you might load it.


You then take 35% of the GVWR (Or max loaded weight for your rig) and calculate how much psi your specific tire needs to support that weight.


So if you have a tire that's rated for 3,860 lb at 80 psi, and another rated at 1,985 at 50 psi...


And a GVWR of 5,400 lb...


...you'd take 35% of 5400 lb = 1,890 lb per tire.


So, you're using 1890 lb as your load.


You then look at your 3,860 lb at 80 psi tire, and divide 1890 by 3,860 = 0.489 or ~ 49%


So, you only need to support ~ 49% of the tires max load, so ~ 40 psi is roughly 49% of 80 psi (you round up for psi).

That's the MINIMUM psi you'd use in that tire on that rig. You then add perhaps 10% of its not an LT tire, and another 10% or so if you drive over 60 mph a lot, etc.

So, somewhere between 40 - 49 psi would be what worked / was projected to work for you.


If you were looking at that 1,985 lb at 50 psi tire, you'd see it would require you to run it at ~ 96% percent of its max load...or about 48 psi, MINIMUM.

There's no psi capacity left to go higher, as the tire only goes to 50 psi max...so, that tire would be too low in load rating to work well.



Most tires have a "sweet spot", a design window where there are the least compromises between hysteresis and contact patch, ideally ~ 60 - 80 % of their load rating....and in a perfect world you shoot for ~ 70%....but anything between 60 - 80% is typically fine.

Too much lower than ~ 60%, the tire is running a bit flatter than ideal, the sidewall will be deforming more vigorously as the tire rolls, there will typically be more heat build-up and lower life, sloppier handling but soft ride....sometimes more edge wear and less center wear.

Too much higher than 80%, and the tire is going to be more bouncy, have more center wear and less edge wear, not conform the contact patch to the road/terrain as well, etc....but may handle more crisply/ride harder.

Shopping for the right tire SHOULD include a look at the max load and psi, but, rarely does, and, the results are people "getting the same tire as other people, but, being unhappy with it"....etc.

>

 

Is there anything this guy doesn't know everything about

Thanks

 

Is there anything this guy doesn't know everything about

Thanks

LOL

I would trade everything I know, no exceptions, for everything I DON'T know, in a heart beat....and come out so far ahead there would be no comparison.

 

35% per tire equals 140% support of your GVWR.

140% of 5400 lbs GVWR is 7560 lbs supported weight?

So its GVWR x .35 / Tire Max Load Rating = Percent of Max PSI x Max PSI = Min PSI x 1.20 = optimal non-LT tire PSI ran over 60 mph per tire.

5400 x .35 = 1890 / 3860 = 0.49 x 80 = 40 x 1.20 = 48 Target PSI..

Approximately 83% of the Max Rated PSI.. A bit high

I'll probably have to make a formula for GVWR, Tire Weight Rating, Max PSI, at a target 70% of max rated PSI. Then find a tire with that Weight Rating and Max PSI for my GVWR

 

The minimum load adds more than the expected 25% per tire, as during braking, etc. weight is transferred to the tires unevenly.

For example, during hard braking, the front tires might have 70% of the rig's weight transferred to them.

That means EACH front tire might have to support ~ 35% of the total weight, all by itself.

If the rigs never moved, 25% for each tire would work at each corner for example.

As your rig is likely TO be in motion from time to time...you need enough capacity to support the transferred weights too.

 

LOL

I would trade everything I know, no exceptions, for everything I DON'T know, in a heart beat....and come out so far ahead there would be no comparison.

That was so profound and deep. But honestly, reading random posts on here you do seem to be one of the more insightful and helpful contributors. Thanks
for all you do.

 

rof-big:

 

Yeahhh, any houses around you for sale tjtj. I'm moving in next door =)