Tire Inflation Guide

wintersun wrote:
Big mistake to go by the tire manufacturers' charts. Use the vehicle manufacturer's recommended pressure as that is what they have designed the suspension for and it is vehicle specific.

Use the charts and the tires will be underinflated and tread life will be shortened and handling will be worse.

Really?

The vehicle unloaded guide will get you per mature tire wear because they want a soft ride. Loaded the over compensate on the rear tires because they have no idea what load you will be adding.

A little common sense and tire weight/inflation charts will give you long tire life. Do you get over 100k from a set of pickup tires? I do.

Big mistake to go by the tire manufacturers' charts. Use the vehicle manufacturer's recommended pressure as that is what they have designed the suspension for and it is vehicle specific.

Use the charts and the tires will be underinflated and tread life will be shortened and handling will be worse.

A couple of thoughts:

First, the maximum pressure listed on the sidewall of tires is a COLD pressure - and the tire is designed to accommodate pressure build up many times what is normal.

In other words, you don't need to worry about allowing for pressure build up. It's already taken care on and you can inflate a tire to its maximum without fear.

Second, a lot has happen since the Ford/Firestone thing a few years ago (year 2000). All the motor vehicle manufacturers have addressed the tire sizing thing by 2008.

However trailer manufacturers are hit and miss. Some have, some haven't. That may be one of the reasons we have such contentious tire threads. We are dealing with vehicles that are marginal on tires.

And lastly - chalk method? Not a fan, because it assumes that a properly inflated tire has a good footprint and over and under have bad ones. That's not a very good assumption. Many tires contact patches don't change much due to pressure (other than length).

Besides, tire wear is more controlled by the vehicle and the way it is used, and not inflation pressure.

A better way is to use pressure buildup. Target is under a 10% pressure buildup. Between 10% and 15%, it should be monitored and adjusted if it continues to be at this level. Over 15%! Immediately stop and do something. Add air, slow down, get a larger capacity tire.

Grandpere wrote:

NC Hauler wrote:

past-MIdirector wrote:
Need to look at the load range on the replacement tires. Most RV replacement tires are one or two load ranges high with a higher max. pressure then what was originally put on. I was taught many moons ago that to be safe air tires to 10% of what the max. pressure is on the tire. This has worked for 40 years now.

Well, I'll admit I've never done that, I've alway's aired to max sidewall rated psi...never added an extra 10% which would be loading a Michelin "E" rated RIBS to 88# instead of 80 and airing my GY G614's to 121 psi instead of the recommended 110psi...one could do that, but again, I've been towing since 75, (and some before that), and also never had an issue... and thats worked for me for almost 40 years also...

My experience has seen most newer RV's with tires on them that are "just close" enough to cover axle rating...as little as the manufacturer can get away with and cut corners on cost. It's rare that I've seen a "G" rated tire where an "E" rated tire would have worked...it's very, very rare.

What he meant was 10% under the maximum pressure, not 10% over the maximum pressure. This was to allow the old bias ply tires to expand pressure from heat and keep them within a safe operating pressure. I also run 100 pounds in my tires that have a max rating of 110 pounds, my dad sold Goodyear & Atlas tires in the 60s and 70s and this is what I was taught. How this theory holds up today with radials I do not know, all I know for sure is that my dad still holds to this theory and it has worked well so I am continuing the tradition. Also, in the old school days, putting the next size bigger tire was also standard practice as auto manufacturers are notorious for putting marginal tires on their vehicles, it looks good on some draftsman's drawings, but in the real world, it hold no water--e.g. the tire debacle with Ford Explorers a few years ago, too small a tire for the weight of the vehicle caused lots of problems. That is why I changed my 8r19.5s for 245x70r19.5s, slightly larger in diameter, much wider foot print, and my mh handles much better. When my van gets new tires this winter, I will jump it 2 sizes 215x70r15 to 235x75r15 they 215s are toooooo small a tire for the weight of the van and at max pressure the sides are still wearing out faster than the centers.

Thank you for the clarification...I read it wrong....:)

NC Hauler wrote:

past-MIdirector wrote:
Need to look at the load range on the replacement tires. Most RV replacement tires are one or two load ranges high with a higher max. pressure then what was originally put on. I was taught many moons ago that to be safe air tires to 10% of what the max. pressure is on the tire. This has worked for 40 years now.

Well, I'll admit I've never done that, I've alway's aired to max sidewall rated psi...never added an extra 10% which would be loading a Michelin "E" rated RIBS to 88# instead of 80 and airing my GY G614's to 121 psi instead of the recommended 110psi...one could do that, but again, I've been towing since 75, (and some before that), and also never had an issue... and thats worked for me for almost 40 years also...

My experience has seen most newer RV's with tires on them that are "just close" enough to cover axle rating...as little as the manufacturer can get away with and cut corners on cost. It's rare that I've seen a "G" rated tire where an "E" rated tire would have worked...it's very, very rare.

What he meant was 10% under the maximum pressure, not 10% over the maximum pressure. This was to allow the old bias ply tires to expand pressure from heat and keep them within a safe operating pressure. I also run 100 pounds in my tires that have a max rating of 110 pounds, my dad sold Goodyear & Atlas tires in the 60s and 70s and this is what I was taught. How this theory holds up today with radials I do not know, all I know for sure is that my dad still holds to this theory and it has worked well so I am continuing the tradition. Also, in the old school days, putting the next size bigger tire was also standard practice as auto manufacturers are notorious for putting marginal tires on their vehicles, it looks good on some draftsman's drawings, but in the real world, it hold no water--e.g. the tire debacle with Ford Explorers a few years ago, too small a tire for the weight of the vehicle caused lots of problems. That is why I changed my 8r19.5s for 245x70r19.5s, slightly larger in diameter, much wider foot print, and my mh handles much better. When my van gets new tires this winter, I will jump it 2 sizes 215x70r15 to 235x75r15 they 215s are toooooo small a tire for the weight of the van and at max pressure the sides are still wearing out faster than the centers.

Cummins12V98 wrote:

NC Hauler wrote:

Cummins12V98 wrote:
Jim your HR came with E tires correct? They recommended max pressure at 80 psi correct? The G tire Carries the same load as the E at the same pressure. So to say HR wants you to run 110 psi on your G tires does not sound right.

Run what you want it's up to you but talk to GY tech they will tell you that you can use the charts for proper inflation based on load when up sizing the load rating.

My 5er has a GVW of 16,950 with 7,000# rated axles...My 5er came with GY G614's..... 110 psi....that's what is listed on the placard on the 5er and that is also what Goodyear recommended.

OK. I saw something about you having E tires must have been on another RV.

Years ago when I owned a Coachmen Somerset (an 04'), it had OEM "E" rated tires.. Can't remember the names, but 5er had a GVW of 14,000# with 6,000# axles. (pin weight was 2400#, (loaded to a little over 13,000#). I removed the tires and put Michelin XPS RIBS on THAT 5er...5er I purchased brand new in 07' (one in my sig), came with GY G614 tires.

NC Hauler wrote:

Cummins12V98 wrote:
Jim your HR came with E tires correct? They recommended max pressure at 80 psi correct? The G tire Carries the same load as the E at the same pressure. So to say HR wants you to run 110 psi on your G tires does not sound right.

Run what you want it's up to you but talk to GY tech they will tell you that you can use the charts for proper inflation based on load when up sizing the load rating.

My 5er has a GVW of 16,950 with 7,000# rated axles...My 5er came with GY G614's..... 110 psi....that's what is listed on the placard on the 5er and that is also what Goodyear recommended.

OK. I saw something about you having E tires must have been on another RV.

Running at or slightly above the load inflation tables will give you:
1. More even tire wear
2. Better braking and traction
3. Better ride quality

Running at sidewall maximum pressure will give you:
1. Cooler running tires
2. Less sidewall squirm and flex
3. Less rolling resistance

Pick what is more important you.

Cummins12V98 wrote:
Jim your HR came with E tires correct? They recommended max pressure at 80 psi correct? The G tire Carries the same load as the E at the same pressure. So to say HR wants you to run 110 psi on your G tires does not sound right.

Run what you want it's up to you but talk to GY tech they will tell you that you can use the charts for proper inflation based on load when up sizing the load rating.

My 5er has a GVW of 16,950 with 7,000# rated axles...My 5er came with GY G614's..... 110 psi....that's what is listed on the placard on the 5er and that is also what Goodyear recommended.

As this is on the TV forum I'm not sure if th OP is referring to his TV or trailer. The TV manufacturer gives recommended pressures. There can be significant differences in side to side weight on trailers so just dividing the weight on the trailer axles by four and airing to the average weight can be risky.