Proper Tire Pressure Questions

[DSolberg]

Greg,
If you read page 35-36 in the book it clearly states; "Once you determine the weight on the wheel position, refer to the tire manufacturer's tire load inflation chart available on its website. For example, a 275/80R22.5 LRG with 5,400 pounds on the left front, 5,100 pounds on the right front, 8,500 on the left-rear duals, and 9,200 on the right-rear duals, for control of the RV it is critical that the tire pressure be the same across the axle". It does not recommend different tire pressures!

Also, if you visit RV Safety & Education Foundation you will find they are weighing coaches by individual wheel position for about $35. Due to economic conditions, they have been limited recently in teams and locations, but may be in your area.

As for trailer brake requirements, there are numerous lists provided by towing experts, the RV Safety & Education Foundation, and others. The list I displayed in the seminar was from Blue Ox a well known towing equipment manufacturer. I do see others have the weight at 3,000 lbs, that is why I suggested contacting your local DMV for their interpretation! Sorry you felt I was giving out the wrong information.

[PhotoMaster]

I did misread the air pressure being the same across the axle. But if the weight on one side says to use one pressure and the weight on the other says to use another pressure, which do you use?

My wife has been searching for days to find someplace with scales in our area, with no luck. How often should it be weighed? What if the scale only tells you total weight? Normally all of my water and holding tanks are kept empty. But if for some reason I have to travel with full tanks, would I need to re-weigh s again? Since there are so many variables, that change frequently, how do I know the correct pressure from trip to trip. There must be a simpler way to know without weighing between every trip?

[ependydad]

Originally Posted by jadatis

The calculator calculates the needed pressure with my own formula wich is better then the American used formula and even better then the European one wich I once got hold of and my tire pressure story began with.

Do you mind me asking what your background is? Are you a tire engineer or something? I'm just surprised to see a homegrown formula being touted as "better" than what the manufacturers recommend.

[cucamelsmd15]

Originally Posted by PhotoMaster

I used to drive full sized dump and jetter trucks, but this has a real drift. I am getting used to it and compensating. For my wife it's a whole new experience.

I never saw the alignment numbers. The RV dealer sent it out to the company they use.

Finding scales around here is a problem. The nearest ones I have found are well over an hour from home.

Ask for the alignment numbers. I generally do all my own alignments, but I'd want to see the numbers. I think that's where your problem really is.

[PhotoMaster]

I'm permanently disable so doing it myself isn't an option. The closest scales are an hour or more away, and if I have to weigh it on each outing it's going to kill me physically as well as financially. My wife plans things very carefully, both time and money wise. The extra hour to 2 hours each trip will put me out of commission way before we reach our destinations. I'm not one to give up, but it would seem really crappy if I had to give up my dream of RVing because of tie pressures!

[ependydad]

Originally Posted by PhotoMaster

I'm permanently disable so doing it myself isn't an option. The closest scales are an hour or more away, and if I have to weigh it on each outing it's going to kill me physically as well as financially. My wife plans things very carefully, both time and money wise. The extra hour to 2 hours each trip will put me out of commission way before we reach our destinations. I'm not one to give up, but it would seem really crappy if I had to give up my dream of RVing because of tie pressures!

IMO, weigh your rig with a "usual" load. Add a margin of X-percent or something and go with those tire pressures. Anything more is daunting even without the physical disabilities. Good on you for still getting out and enjoying things.

[PhotoMaster]

Thanks. It's times like these I get so frustrated that the idea of living easier is actually becoming more complicated.

[ependydad]

Originally Posted by PhotoMaster

Thanks. It's times like these I get so frustrated that the idea of living easier is actually becoming more complicated.

I have a tendency to get "wrapped around the axle" on the minutia of details and have to remind myself to step back, breathe and focus on what is important. In my opinion and no disrespect meant (because I can say the same about myself on many things) - you're over thinking this. It's wholly unrealistic to worry about exact wheel weights and constant weighing. Weigh yourself, figure it to an average, pad it and go with that. Maybe repeat in a couple of years if you find you normally carry water, or more and more "stuff" has snuck (sneaked?) into the camper.

Get a ballpark and go have fun.

[cucamelsmd15]

2nd on use a ballpark, set and forget. We run the to her home tires with a set up for 75,000 pounds, even though our down the road weight is usually closer to 68,000 pounds. Check them before each trip once they're set and call it a day.

[jadatis]

Originally Posted by ependydad

Do you mind me asking what your background is? Are you a tire engineer or something? I'm just surprised to see a homegrown formula being touted as "better" than what the manufacturers recommend.

I can put the whole story here but best would be if I explaine it in next topic about extra save pressure loadcapacity lists.
http://www.forestriverforums.com/for...sts-37637.html

Then if someone else asks I can point to that topic, and dont have to do the whole story again and hyjack anothers topic.

[SKnight]

Originally Posted by PhotoMaster

Thanks. It's times like these I get so frustrated that the idea of living easier is actually becoming more complicated.

I've got to ask, why worry so much about it? It's just air pressure, have properly rated tires, set the air pressure to spec max and go camping.

At the end of the day, despite experts proclaiming that you need to weigh each axle and come up with some magic number then set your final pressure with the tire at a known max temperature to 76.5PSI, just set them to the spec as researched by the manufacturer.

Nobody has ever been hurt by a tire that's loaded within it's load range and the owner set the pressure to spec, defects or extreme age withstanding. Trust me, considering that the vast majority are running low on pressure you're in good shape.

[spicyrv]

Greg (PhotoMaster), I think you're right about the "expert" - sometimes they're mistaken or just have wrong information. An RV expert is likely not a tire expert - that would be the engineer that designs the tires and knows all those formulas about loads, stresses, etc.

I set my tires to the recommended pressure and go. I also have tire pressure monitors - something I highly recommend.