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View Full Version : Am I Doing This Wrong - Tire Inflation


masterdrago
12-09-2019, 06:58 PM
I looked around on this and a few other RV forums but got no clear answer. I've always inflated my Sailun St235/80R16 to near max - 110psi. When I had my individual wheel weight taken, I was told to inflate to the load. Well, the load is different on each tire. See load & margins....


https://i.imgur.com/cODyISY.jpg



If you take a look at the charts and weights, I should have the tires inflated from 60-85 psi, not 110, depending on which tire:confused: When inflated at those levels, the tire does not look right and will have extremely high wear on the outside edges. What does this experienced crowd think?

DQDick
12-09-2019, 07:47 PM
Never have inflated to the load. Always inflated to about 108. We're close to 90,000 miles now on two rigs and it works for us so we'll keep doing it.

rohrmann
12-09-2019, 08:04 PM
As long as I am at between 105 and 110, hopefully closer to 110, I'm happy and our tires wear just fine. I have read that you should take the highest loaded wheel, add 10% to that and inflate all the tires to that weight on the chart. If you don't want to mess with that, you just inflate to the max cold pressure on the sidewall. I figure, the little extra pressure will reduce the rolling resistance a little bit more than the lower pressures and it will make towing easier and maybe save a little bit of fuel.

jeffba
12-10-2019, 05:04 AM
I inflate to the sticker on the side of the camper

masterdrago
12-10-2019, 06:53 AM
I inflate to the sticker on the side of the camper Same here until just now hearing this new thought from https://rvsafety.com/ when we did the individual wheel weights in Buda, Texas. Their web page does not list Sailun. My Sticker and max on tire say 110 and I've been doing for two years. I've always checked the cold pressure at around 70 degrees in the early morning b4 running up the road unless it is crazy cold. Then I let the TPMS relay the pressure and scream that they are low, then cancel it and roll and watch. In really hot weather on the sunny side, I've seen near 125psi. Asked my guys at Discount Tire since I could not reach Sailun and they said that "over pressure" was designed into the tire. Their similar brand is Heartland. So, I'm sticking with the way I've done from the beginning. Thanks for the "pro" answers.

mazboy
12-10-2019, 07:23 AM
Same here....inflate to near the rated pressure...

ChuckS
12-10-2019, 08:26 AM
If you have heavy wear in outside edges of those Sailuns it’s not caused by running 110 psi cold. Furthermore to run those Sailuns at less than 105 is negating the load capacity of the tire and causing the sidewalls to flex.. This in turn will create heat build up and cause issues.

Run them between 105 and 110 and if your axle alignment is good they will wear very even across from edge to edge

Skw774
12-10-2019, 10:16 AM
if inflate to load was the case you would be adjusting your tire pressure all the time on your car. depending on how many people get in and ride that day

Dave W
12-10-2019, 10:38 AM
I've seen where others on a different and SOB forum did that same set of calculations. Their choice, their time. I just inflate to the max tire capacity psig and have --- for a long time. No wear, rear or worry. My truck - heavier on the LH side with me, a DEF and fuel tank. I still inflate at sticker when towing and 5 psig less when not. I would go 5-8 psig less but the TPMS will tell me I have a low tire.

mlh
12-10-2019, 03:03 PM
Relax. You are making this way too complicated. The chart gives you the pressure you can carry a load safely. You can carry the same load safer with little heat build up at max pressure.
Lynwood

7.3Ford
12-10-2019, 03:09 PM
I ordered my 5th wheel with G-614, and the sticker Montana put on my trailer says 110 psi, so that is what I always do.

BB_TX
12-10-2019, 07:11 PM
I tend to believe the tire manufacturers and tire dealers publish load vs inflation charts because of their expertise, not just something to pass the time. While inflating to the max stated pressure is certainly better than being under inflated, max pressure probably most often falls in the category of over inflated.

Tire manufacturers and dealers information are typically fairly consistent in the following statements;
Under inflation will cause tire over heating
Under inflation will cause increased edge wear
Over inflation will cause a harsher ride
Over inflation will cause increased center wear
Over inflation will cause a harder tire making it more prone to damage and puncture due to impact
Correct inflation for the load provides more even contact to the road across the width of the tread meaning best traction also meaning better braking

If weights are not known then max is the safe way to go. And easiest. If individual weights are known, then it is generally recommended to inflate all tires to the pressure (or slightly higher) recommended for the tire carrying the most weight.

CalandLinda
12-11-2019, 04:58 PM
I looked around on this and a few other RV forums but got no clear answer. I've always inflated my Sailun St235/80R16 to near max - 110psi. When I had my individual wheel weight taken, I was told to inflate to the load. Well, the load is different on each tire. See load & margins....Tire industry standards state, in part, that all tires on a single axle need to be inflated to the one carrying the highest load. Notice I said "in part". That's because there is more to it than that and I may touch on it later, below or in another related post.


https://i.imgur.com/cODyISY.jpg



If you take a look at the charts and weights, I should have the tires inflated from 60-85 psi, not 110, depending on which tire:confused: When inflated at those levels, the tire does not look right and will have extremely high wear on the outside edges. What does this experienced crowd think?

your "charts and weights" must be used in conjunction with established standards. When inflating your tires to the load carried they have no load capacity reserves.

CalandLinda
12-11-2019, 05:23 PM
I tend to believe the tire manufacturers and tire dealers publish load vs inflation charts because of their expertise, not just something to pass the time. While inflating to the max stated pressure is certainly better than being under inflated, max pressure probably most often falls in the category of over inflated.

Tire manufacturers and dealers information are typically fairly consistent in the following statements;
Under inflation will cause tire over heating
Under inflation will cause increased edge wear
Over inflation will cause a harsher ride
Over inflation will cause increased center wear
Over inflation will cause a harder tire making it more prone to damage and puncture due to impact
Correct inflation for the load provides more even contact to the road across the width of the tread meaning best traction also meaning better braking

If weights are not known then max is the safe way to go. :iagree: And easiest. If individual weights are known, then it is generally recommended to inflate all tires to the pressure (or slightly higher) recommended for the tire carrying the most weight. How about the next trip? Or the one after that? Or the return trip? Did you add water and not dump it? Going to the load carried just might require a trip to some scales that can give you individual wheel loads for every trip. Doesn't that sound a little commercial? Yup, that's because it is.

What is the start of "under inflated" or "over inflated". Something must have been established to have such descriptions. Just maybe it's the vehicle manufacturer's recommendation. Just for the record, those vehicle manufacturer recommendations for the OE tires are considered MINIMUM. They may be best described in this statement. Any tire found with an inflation pressure 20% below recommendation is considered to be in a "run flat" condition and should have an internal inspection to determine damages.

On the other end; tires inflated above what is shown on their sidewall may be "over inflated"

RV trailer tires are not required to have the load capacity reserves the auto industry provides with their vehicles. RVIA has stepped-in with a 10% load capacity reserve policy/recommendation above vehicle certified GAWRs for all RV Trailer OEM tires. However, it's probably not going to be enough, in many cases, because RV trailers are notorious for having at least one wheel position with an overloaded tire.

JABURKHOLDER
12-11-2019, 05:49 PM
Letís look at this more practically. Do you own four individual wheel scales ?
If not, do you want to purchase them ? Do you want to park on individual wheel scales every time you set up at a campsite ?
How about this; do I check the weight before or after I dump ? Do I weigh every time I take something out of the fridge ? Do I weigh with the slides in or out ?
Too much ! :facepalm:
I have a 2016 3791RD with the g-614ís and inflate ALL tires to a minimum of 105psi.
Firm believer in kiss

uhftx
12-12-2019, 01:13 PM
Look at your car or suv. The max pressure on the sidewall may state 32 but the MFR of the car states the tire pressure is different for the front two tires vs the rear two tires or something close. IT could be 24 rear and 27 front. This to get even tire wear. Generally the front of the car or Suv is heavier due to engine and front passenger weights.


The tires on our RV units are closer together than the distance on a car truck or suv. So they should most likely be the same all around with only a few inches.


I just purchased 5 sailun tires and 4 rims. My old ones were 80PSI rims. My 3255rl has a max rating of 12,600 or maybe 12,800. I don't remember exactly. I switched because my trailer had LT tires and the load range D Tires were still causing a few blowouts (most likely due to age and sitting in the yard) But I liked the fact that Load Range G was an option. Even thought I do not need to go to 110PSI. I now have a huge margin of safety. And maybe a softer ride for the camper with something less than 110PSI with my mind at ease. Which is what it is all about. NOw I just have to retire and enjoy life.



Here is what I heard from an old timer construction equipment repair guy. IF you jack up each axle and place a contact sheet. (He used and example of black construction paper arts and crafts type. Sprinkle it with flour and put the tire down off the jack) Jack it back up and gently remove the sheet and measure the square inches of the tire impression Length X Width equals area. Take the tire pressure in Pounds Per Square Inch. Divide your contact area number from above and divide that by the tire pressure and you will be within 10 to 15% of the actual weight of the equipment. This works even if you have 4 or 6 or more tires. You could get the weight of everything without having to go to a commercial scale Of course he always claimed he was under 10% error. Just make sure you are on a level hard surface, NOT MUD or gravel.

masterdrago
12-13-2019, 05:58 AM
Letís look at this more practically. Do you own four individual wheel scales ?
If not, do you want to purchase them ? Do you want to park on individual wheel scales every time you set up at a campsite ?
How about this; do I check the weight before or after I dump ? Do I weigh every time I take something out of the fridge ? Do I weigh with the slides in or out ?
Too much ! :facepalm:
I have a 2016 3791RD with the g-614ís and inflate ALL tires to a minimum of 105psi.
Firm believer in kiss As usual, Burk, you make clear and concise points. So no to all.... thanks but I always weigh AFTER I take a dump:thumbsup:

Bill M
12-15-2019, 01:33 PM
Although Sailuns can be filled to 110 psi, are your rims rated for that 110? If not you are limited to 80 psi & 65 mph max speed. Run at max cold pressure period.

CalandLinda
12-15-2019, 02:27 PM
Although Sailuns can be filled to 110 psi, are your rims rated for that 110? If not you are limited to 80 psi & 65 mph max speed. Run at max cold pressure period.

Inflation pressures and speed ratings abide to their own individual standards.

Recommended cold tire inflation pressures for RV trailers are set by the trailer manufacturer and are minimum requirements.

Tire speed ratings are set by individual tire brand manufacturer's. At their maximum value - maybe 75 MPH - they provide 100% of the tire's maximum load capacity.

RV trailer tires without some form of speed limit displayed on their sidewalls default to the TRA standard, 65 MPH.

laverdur
12-15-2019, 03:27 PM
I agree with rohrmann. I run my G614s at 110 psi. I get great wear and good fuel economy, considering the load. Any one who has upgraded from LR E tires to LR G tires should ignore the manufacturer's sticker on the RV. It will say 80 psi when it needs to be higher.

CalandLinda
12-15-2019, 10:04 PM
I agree with rohrmann. I run my G614s at 110 psi. I get great wear and good fuel economy, considering the load. Any one who has upgraded from LR E tires to LR G tires should ignore the manufacturer's sticker on the RV. It will say 80 psi when it needs to be higher.

The sticker (federal certification label) has the minimum PSI setting for the Original Equipment tires. The minimum requirement for replacement tires is a PSI setting that will provide the load capacity the OE tires provided at vehicle manufacturer's recommended cold inflation PSI. All inflation pressures above that recommendation, up to and including tire sidewall MAX, are optional.

goodellj
12-16-2019, 07:57 AM
I started with OEM E-rated tires and the inflation pressure on the sticker was 80psi. After installing a TPMS and several blowouts and complete tire changes, I finally wised up and got G-rated tires which on the sidewall called for 80-95psi. I knew I needed to use a higher cold inflation pressure but I was not sure how high to go. I decided on 90psi.

When you are rolling the tire pressures quickly rise by 5-10lbs, especially in warm temps. On a trip we would routinely be at 105psi, so I decided that these 5lbs weren't all that critical because the pressures rise anyway.

PSFORD99
12-16-2019, 10:46 AM
I started with OEM E-rated tires and the inflation pressure on the sticker was 80psi. After installing a TPMS and several blowouts and complete tire changes, I finally wised up and got G-rated tires which on the sidewall called for 80-95psi. I knew I needed to use a higher cold inflation pressure but I was not sure how high to go. I decided on 90psi.

When you are rolling the tire pressures quickly rise by 5-10lbs, especially in warm temps. On a trip we would routinely be at 105psi, so I decided that these 5lbs weren't all that critical because the pressures rise anyway.


I have to ask, what G rated tire did you buy that had 80-95 marked on the sidewall.

goodellj
12-16-2019, 10:57 AM
Gladiators. It also says they were made in China! They've been on the trailer for 3+ years and 29,440 miles. And they are showing very little signs of wear.

PSFORD99
12-16-2019, 12:57 PM
Gladiators. It also says they were made in China! They've been on the trailer for 3+ years and 29,440 miles. And they are showing very little signs of wear.

Gladiators, have heard of them ,just not that range of air pressure on G rated tires . Sounds like you are happy with them. Thanks

masterdrago
12-17-2019, 08:26 PM
So to follow up on this, has anyone figured out some sort of graph indicating a pressure temperature relation? So I get up to leave a campground and check all my tire pressures @80 degrees. Shows 100psi. When leaving the next campground the ambient temperature is 28 degrees. Should I now air up my tires to the sticker on the tire and tag on 5r? I know that my TV has a large swing of pressure during large swings in temperature. My tires usually run about 8-10 degrees over the ambient when driving based on my TPMS.

JABURKHOLDER
12-18-2019, 02:13 PM
masterdrago,

Thanks for your comment.

Moving forward, I do not have a temp/psi graph but letís make this even harder. One side of the RV is in the shade, one side is in the sun. The tires are covered, or not. One side of the RV has a slide that covers the tires.

Overthinking this whole process.

The morning of departure, regardless of any load or weather, I air my all RV tires to 105psi.

Again, firm believer in k.i.s.s.

masterdrago
12-18-2019, 05:49 PM
masterdrago,

Thanks for your comment.

Moving forward, I do not have a temp/psi graph but letís make this even harder. One side of the RV is in the shade, one side is in the sun. The tires are covered, or not. One side of the RV has a slide that covers the tires.

Overthinking this whole process.

The morning of departure, regardless of any load or weather, I air my all RV tires to 105psi.

Again, firm believer in k.i.s.s. Okay. So it's 57 here now all tire pressures are from 85-90psi. TPMS has to be quenched due to squealing that they are low. If I air to 105 now, how over-pressured will they be when the tire temp is 105. A good guess might be 109 if we read all the info on the newt correctly. I've found real life numbers much higher. As much as 128psi rolling in 95+ weather.

JABURKHOLDER
12-18-2019, 05:58 PM
All taken into account by the tire manufacturer when they determine the tireís max psi.

Youíll make yourself crazy thinking about all the what ifís.

Still, and always will believe in k.i.s.s.

laverdur
12-18-2019, 06:39 PM
As was previously stated, tire manufacturers take normal operating conditions into account when designing a tire and specifying the max inflation pressure. Some sources say that for every 10 degrees in temperature variation, you will see a 1-2 psi change in tire pressure. Altitude also affects tire pressure to the tune of about 2-3 psi per 5,000 feet elevation change. Sun on the road and the color of the pavement will also effect tire pressure. On a bright sunny day, a white/gray concrete road will not absorb as much heat as a blacktop road. The tires will pick up some of that heat from the roadway. I carry an infrared thermometer and during rest stops I check road temperature and tire temperatures. I also hub temperatures and disc/drum temperatures. It only takes a couple minutes to check all 8 wheels. Tires on the sunny side of the rig will be warmer than those on the shady side. Proper tire inflation will ensure that the tire is running as cool as it can under the prevailing driving conditions. A cooler tire has less temperature rise. I have started towing days on a valley floor of 1,000 feet at 55 degrees. During the day I would experience temperatures up to 100 degrees and I would have elevation changes of up to 7,500 feet. My TPMS has never screamed at me for tires being over temperature or over pressure and I it set to be more sensitive than the default settings. I stick with 110 psi and I've had good luck for over 80,000 miles.

mhs4771
12-18-2019, 06:46 PM
All I know is that the Max Inflation Pressure on the Sidewall is taken at 70 degrees F