CTDwannaB

I took a look at the tire inflation information on the door sticker of the truck I'll be picking up next week and found the posted maximum inflation pressure confusing. The truck is a dually with General Tire LT235/80 17E tires which I assume are rated for 80psi max (should have read the fine print on the side wall but couldn't read it with these stupid tri-focals). The door sticky says 65 psi maximum. The Goodyear load/inflation table I have rates a tire of this size at 2470 lbs in dually configuration at 65 psi and 2835 at 80 psi. Certainly 65 psi will handle the truck plus the 1800 lb hitch weight of my trailer but I had planned to tow with a tire pressure between 70 and 75 for sake of reduced tire flex, better economy, and tire temperature at highway speed. How should the posted inflation information be interpreted? Does it mean that I shouldn't exceed 65 psi? If so can someone tell me why?

I couldn't resist taking the truck for a short drive and fell in love with it instantly. I like the feel of the 2WD compared to the 4WD's I've test driven, maybe because my last truck was a 2WD 2500 and I'm used to the lower stance. The shift of the NV5600 will take a little getting used to, especially since the last manual I drove regularly was a Celica 5-speed.

Some of my staff at the museum where I work were disappointed I couldn't pick up the truck an park it on the museum lawn today. We were celebrating Earth Day with a bunch of family and kid's programs and a couple of the local dealers were bringing in a Smart Car and a couple of gas/electric hybrids. Seems they wanted to use my truck as a bad example.

Dave

djbikeman

I helped put together Omaha's Earthday celebration from 2001-2004. I was responsible for setting up the grounds area and all the coordinated efforts of volunteers.

I had some granola walk up to me one year and ask how I could drive a big truck (at the time, it was an F250 Crewcab Superduty) to an Earthday event. I asked him if he thought it would be OK to tow the 30ft trailer with two golf carts, tents, chairs, tables, etc with a Honda Hybrid or Toyota Prius.

Fuel efficiency is relative. I got the job done in one trip, less then 2 gallons of fuel. Any other way would have expended more energy.

So when that guy wants to use your truck as the "bad" example, make sure you set him straight. I USE my truck. It is always loaded for work and I have done a lot to make sure it is as fuel efficient as possible.

I'm sure the granola didn't care either way, just wanted to voice an opinion, but he voiced it to the wrong guy. At that time, I used to drive my truck when I needed it, and ride my bike to work otherwise (usually 3-4 days a week). I do the recycling thing, and generally try and conserve, but there is a need and place for large trucks in a conserving world.

My job now makes it impossible to ride to work, but I still do my best to conserve.

gatf4

I believe that the pressures listed are the Pressures that Dodge suggests for best ride and handling. You can certainly go to the max of 80 if you need the extra capacity.

Hemi Cat

Max tire inflation should always be determined from the sidewall of the tire you are inflating. The lower inflations are probably on a load range D tire, and the higher inflation is probably a load range E tire. The max pressures should always be run when hauling a heavy load. You get better fuel economy with the tires inflated to max psi but the trade offs are a harder ride and more tire tread wear in the center of the tread. I generally run 5-10 psi under max inflation on my trucks all the time, but I carry weight quite frequently and don't want to mess with tire pressures constantly, and like the better fuel economy when empty.
The door sticker has tire pressures for the stock tires that it left the factory with. Different tires have different load ratings and weight ratings and max inflation ratings. You have to read the small fine print to be sure.

SuperGewl

Here is the real fat and skinny on tire inflation for all cars and trucks. You should use what the manufacture states which is in the Tire Inflation Guide that is in the glove box. Yes the tires mave a MAX inflation of 80psi but that is NOT what DC states to inflate to. The tires are designed to be used on various automoblies and in different situations. The dually tires are NOT suppose to be inflated to 80psi because they will end up touching against each other which is not good to have.
The reccomended inflation for the SRW 3500 is 75psi loaded and 40 psi unloaded, front pressure is 55psi unloaded and 65 psi.

bulabula

Gewl, you've got some wires crossed.

The tires shouldn't be close to touching at max tire inflation. It when you run them under inflated, you can run the risk of the tire bulges at the bottom of the tires touching/rubbing; that will contribute to premature heating and tire failure.

CRXsi

The other major thing to consider with tire pressures is that engineers spend countless hours determining which pressures are right for a given vehicle and given load. Of course when you go up in pressure the load rating goes up but the major downside most people don't consider is that your contact patch to the road decreases. As it is there is a VERY small area of the tire that actually contacts the road and maintains the control of the vehicle during cornering, braking and emergency situations. Take into account rain, mud or snowy situations and things become exponentially worse. I'm not saying it is a bad idea to increase pressures if you are hauling but do consider that the reason you get more center tread wear is because this is the only part of the tire doing the work (the only real contact patch). The same is said about under inflating because only the shoulders of the tire are contacting the road. Ideally you want the whole tread surface to be contacting the road from the VERY small contact patch otherwise you will not be getting maximum traction capabilities from that contact patch if a situation arises that you need to rely on it. Race cars are very picky regarding this contact patch and racers can vary tire pressure by less than 0.5psi between runs to change the handling of the car...sometimes drastically, and not everyday or track or condition is the same. (see my pictures for my other hobby) and this is why engineers come up with the recommended tire pressure ratings because based on their research these are the settings that generally give the best safety margin for load, handling/safety/braking, ride comfort and fuel mileage.

My thoughts, not yours.

GMScott

Well, I have run my tires at the recommended max on the door sticker and the rear tires are now prematurely shot at 56K miles. Mostly worn in the middle as over-inflated although my truck is loaded most of the time. Front tires were rotated side-to-side and are in great condition. I saw the wear happening, but with the combination of me being lazy, the lousy weather (cold) and having to remove the skins to get to the valves I let them go. I also knew that I would be replacing them in the Spring with a taller size and highway tread. My stock tires were on/off road and the dealer would not switch them for me, claiming he got "beat up" on my trade.
Anyway, I will be running the new tires on the rears a little softer.

CRXsi

Good point about tire wear, if your tires are wearing more in the middle, or on the shoulders it doesn't hurt to modify your tire pressures, again this would indicate that tread contact is not optimum under your situations. In the racing world we use what is called a tire pyrometer to monitor tire temps across 3 spots on the tread surface after every track session to adjust tire pressures and alignment settings so that maximum tread contact is estabished. Keep in mind that tire pressures also change approx. 1psi for every 10°f in temp change. The ratings on the door are for cold inflation pressures.

CTDwannaB

Thanks for your feedback. I think I'll try running at the recommended 65 psi with the trailer.

Dave

4x4not

One way to REALLY check pressures is to do the chalk test. Draw a line across the tread and drive STRAIGHT in a parking lot. See where the chalk is worn off. If you need to, adjust your pressures accordingly. I'm running my stock tires @ the door pressures now but plan on doing the chalk test soon (just don't have any chalk )

Dorkweed

On my '99 I got 125,000 miles on the original Michelin LTX M&S tires; size 245/75 16. I ran those at 70psi front and rear all the time because I tow my work trailer during the week and do not want to be bleeding air off and then refilling them. On my 04.5 with Michelin LTX AS, I also run them at 70psi, and can see no visual signs of wear on them at close to 20,000 miles now. Run them hard and they will last longer.