Colorado B.S. Thread

This actually seems to be how it works on my Ram 2500. ABS almost rarely engages, but the other day I needed to bring it down from 60mph to near 0 in a lot less than a football field so I tried to put my foot through the floor. As speed started to drop quickly, and lockup/skidding started to happen, ABS kicked in for maybe the last few yards. It'll also kick in if I'm driving down an icy/snowy hill and hit the brakes too hard. All times where there has been excessive wheel lockup while the truck had good forward momentum. Which I think actually is a pretty good execution of the system for it's intended purposes. The other thing my truck will do is temporarily engage the tow/haul mode under hard breaking so there's more engine breaking going on so I can be lighter on the brake pedal. I'm pretty surprised that Chrysler may have gotten something almost right.

 

Inflate them more the say 35-40 and you will get a stiffer tire that gets better mpg. But the compromise is watching how the tire wears. If that pressure is to much you will see the center of the tire wear faster then the outer. And oposite if its under. Ride also effects it for me. To much and it hurts going over things to little and i feel everything floats and takes a second to catch up (talking about 12 psi from wheeling kinda psi)

Larger side walls will like lower psi to keep a happy ballance in wear then smaller side walls.

 

A trick since all vehicles are slightly different regarding load and driving style and all that...

Setup your truck how you normally drive. Put your normal stuff in the bed and cab, etc. Inflate your tires to something reasonable like 40lbs or so, the 80lbs rating is max air pressure and has nothing to do with daily driving pressure. Then grab a big piece of sidewalk chalk and draw a line straight across the tread from sidewall to sidewall. Then go drive around the block. See how the chalk wore down. If the whole line was scrubbed off evenly you're at a good pressure. If the middle is gone but the sides are still there, lower pressure. If the sides are gone and the middle is still there, add pressure. If you have to add or lower pressure, redo chalk test until the whole line is being scrubbed evenly. That'll be the pressure for those tires on your truck under normal circumstances. Adding a bunch of weight, towing, etc will change the variables and also change the optimal pressure.

 

Chalk is the right way to set pressure

 

Cool, makes sense. Thanks for the info!

Holy shit. That's magical. Thanks for the tip!! I'll do that this weekend!

 

Yeah I tried the chalk test a few weeks ago. Completely ineffective for me. According to the results my fronts should be at 45 and my rears at 25. Sidewalls bulging like I was aired down on a trail and still not getting even wear across the rear, didn't see much of a difference in the front over a 15psi range.

In the past I ran 32-35 in 265/75/16 Ds. Over 20k miles of wear, considering they were used to begin with, it seemed to me like that was just about right but slightly on the high side. With these 235/85/16 Es Discount had them at like 45 or 50 after install in March. That was clearly too high based on ride stiffness and handling, but I wasn't sure how much on the handling part since I'd gone to a slightly taller and rather narrower tire. After a week or so I dropped it to 32ish, being what I'd run before, and it was a lot better.

But I wanted to try the chalk test and see if I could get the 'right' pressure, so eventually I got around to it. I started at 40psi (according to my primary gauge, more on that in a sec) and then tested and rechalked my way down to 20psi in 5psi increments. It was on a pretty new and smooth asphalt parking lot, so cracks and warping shouldn't have been a factor, but I honestly didn't see a lot of difference as I went - nothing as clear as all the photos and videos of the technique seem to show. Eventually I settled on 35 on the primary gauge. Which happens to be a Brookstone electronic that isn't having battery issues and always produces consistent readings, but when compared to two different pencil gauges seems to read 2-5psi low. So I think I'm actually at 39.

Having gotten used to the new tire characteristics, it feels like my old ones - a little on the high side and stiff, but just enough to know it. I know part of the problem is running E loads on such a light truck. I'll be keeping an eye on wear, but I'm only coming up on first rotation now. I think the outside block corners are wearing a bit faster in the front, but I also noticed I seem to have a bit much camber in the front now. Or at least I never noticed them in quite the V before. I've never changed any suspension components or had an alignment done for that matter, so I'm not sure if I need one a) because it's past time or I did something, b) because the tires are so different than stock, or c) I don't and it's just the taller skinnier tires making it look like I do.

How many of you run different front and rear pressure, temporary load adjustments notwithstanding?

 

Figured I better get on this while mother nature still smiling down upon us.

 

you were right, it's the rack

 

Tire pressure is probably one of the top 10 most debated subjects in the history of the universe.

 

I'm just gonna let it go for now and keep the tires rotated

 

to set the correct pressure for even wear: chalk test

 

Chalk a line on the sidewall then go do some figure 8s increase pressureslowly and repeat until chalk doesn't disappear

 

Set pressure by monitoring tire wear. Look a scrub across a dirty, flat floor. Just guess and call it a day.

 

whats Jack drilling holes in a plate for? doesn't he have some HW to do?

 

Remember kids. Bring propper saftey clothes to work.


This is a no no...


This is a yes yes..

 

metal shards inbetween those open holes will be FUN FUN FUN!!!

 

Helloooooooooooooooo Colorado!