uneven tire pressure buildup while towing with airbags

[Smokey_Lew]

Hi everyone, here's thanking you in advance for any help you might suggest for this air pressure buildup issue I'm experiencing.

I'm towing a 25' TT with my 2011 Dodge Ram 1500 and using Firestone "Coil-Rite / Work-Rite" air bags. While towing, I pressure the bags to 30lb using a compressor mounted next to the battery under the hood. The issue I'm having is that the Ram's tire pressure monitor consistently shows my right rear tire building up three lbs. more pressure than the left tire while towing.

I set my tires to their maximum 50 lbs cold pressure as stated on the sidewall before towing. The two front tires will build pressure to about 54 or 55 lbs. while the rear tires will build to about the same on the left but about 3 lbs more on the right. In this example, 55 to 57 on the left and 57 to 59 on the right depending on how hot the outside air temp. is. I try to keep the towing speed at between 60 and 65 mph.

Any ideas on what may be going on? Could it be an air bag issue? The tire pressures stay consistent right and left when the bags are not inflated (normal pressures set at 35lbs all around) and I'm not towing. The people who installed the bags for me said they have never heard of this kind of a problem related to the air bags. Any help would be appreciated.

[Turtle_n_Peeps]

My question is why are you worried about 2 or 3 lbs or tire pressure?

If you don't want the tire to go up in pressure just bleed all the air off and fill with nitrogen. Bleed it off again and fill with nitrogen again. This will get both tires around the same pressure going down the road.

[Dave_Mck]

Try towing without the airbags inflated and see what happens

[Dave_Mck]

rhagfo wrote:
The right rear will carry a bit more load and drag due to road crown.

Good point. I was at my buddy's shop the other day having the alignment done. He was showing me how the machine works as he was setting the wheels right. He didn't make it perfectly straight, he explained that they have to be slightly off due to the crown of the road. If you make it perfectly dead on straight your car will always want to go off to the right with the slope of the road,.

[Smokey_Lew]

I think you may have hit the nail on the head with this answer. I use an Equalizer hitch and it always seems that the right spring bar takes more effort to place up on the bracket than the left one. Not sue why but I'm definitely going to have to look into this. Thanks for your suggestion.

[mkirsch]

Funny, the only online reference I can find to "Komfort 253tqs" are RV.net posts from you!

At least I finally found a picture of your rig to confirm that it's a travel trailer and not a 5th wheel.

If you are using WD bars, there might be more tension on the left bar, which will in turn put more pressure on the right rear wheel (or more correctly, LESS pressure on the left rear wheel). Trailers can be heavy on one side due to their floor plan, slides, etc..

[rhagfo]

The right rear will carry a bit more load and drag due to road crown.

[Smokey_Lew]

Wow! Brilliant suggestions. I'm a worrier by nature and all this is good medicine for me. Thanks!

[All_I_could_aff]

A few possible reasons:
1) slightly more weight on that corner of truck
2) slightly more brake drag (heat)
3) slightly more percentage of torque to that wheel (heat)
4) exaust pipe on that side (heat)

[fj12ryder]

When the pressure has stabilized and the pressures show their difference, I would get an non contact heat gun to check the tires/wheels. It's possible you're building up more heat on one side than the other. This would lead to different pressure readings.

[carringb]

Smokey Lew wrote:
Hi Bryan, thanks for your quick response. The setup I have for the bags is a compressor under the hood of the truck that feeds both bags form a single line. The airbag gauge shows the pressure from that single feed line. I guess you have to assume the pressure in both bags is equal. I think my next step is to pressure up the bags and get under the truck and spray some soapy wanter on the lines and see if I get any bubbles.

Got it. In your case the single air line should balance pressure in the air bags, which means both tires should be roughly equally loaded. So... I'd lean towards normal tire variation.

[Bedlam]

Rotate the wheels and see if the difference follows the tire or is relative to that position on the vehicle.

[Smokey_Lew]

Hi Bryan, thanks for your quick response. The setup I have for the bags is a compressor under the hood of the truck that feeds both bags form a single line. The airbag gauge shows the pressure from that single feed line. I guess you have to assume the pressure in both bags is equal. I think my next step is to pressure up the bags and get under the truck and spray some soapy wanter on the lines and see if I get any bubbles.

[carringb]

Have you verified air-bag pressure after towing? I slight leak in one of the airbags will cause the opposite tire to carry little more of the load. At this point however, I would not consider the difference enough to really worry about. You might just need to top off the leaky airbag (most likely a leaky fitting really) partway through a drive. A very small leak might not leak at all when the the lower pressures you run unloaded.

Another possibility is simply normal variance in the internal telling resistance of you tires, or maybe even a slight tread height variance, which happens after normal tire rotations (and even out as they wear more).