Compressor to put air in RV tires?

[RHeald]

I have purchased a couple of compressors to put air in the RV tires. However, I returned them because they did not work. I would like one that I could carry with us in the coach. Could somone recommend one? I need a compressor that is small but powerful. We need 95 psi in all the tires. Thanks.

[wolfe10]

I have purchased a couple of compressors to put air in the RV tires. However, I returned them because they did not work. I would like one that I could carry with us in the coach. Could somone recommend one? I need a compressor that is small but powerful. We need 95 psi in all the tires.

Welcome to the FMCA Forum.

What kind of coach/chassis do you have? Does it have an on-board air system?

And, as a side note, is the 95 PSI in all tires based on the tire manufacturer's recommendation for your actual weight? It is unusual that the fronts and rears would work out to the same PSI.

Brett Wolfe

[NWJeeper]

I have purchased a couple of compressors to put air in the RV tires. However, I returned them because they did not work. I would like one that I could carry with us in the coach. Could somone recommend one? I need a compressor that is small but powerful. We need 95 psi in all the tires.

The way I got around this with our previous motorhome was to buy a 5hp compressor mounted on a 20gal tank at Lowes. It was a rebuilt unit so the price was right. I removed the pump from the tank, mounted it to a plate and then mounted it in a side compartment. It was hardwired to the A/C power and plumbed to the tank which I welded tabs to the side of and bolted in between the frame rails under the rig. I had no problems airing up my tires as a 5hp compressor airs up to 120psi, but more importantly I had the CFM to do it in a reasonable time frame as well as being able to run air tools for removing lug nuts on the rig or the toad.

I know this kind of project is beyond what a lot of people want to get into but it was fun to do and if you have the right tools and the do-it-yourself spirit it's not that hard.

The problem with most small portable compressors is that they lack the CFM which is the true measure of how long it will take to air up your tires and it is very misunderstood by consumers. A compressor with 120psi but no CFM will take all day to air up a single RV tire. More importantly compressors with to little CFM will work themselves to death trying to air up an RV tire.

[RHeald]

Welcome to the FMCA Forum.

What kind of coach/chassis do you have? Does it have an on-board air system?

And, as a side note, is the 95 PSI in all tires based on the tire manufacturer's recommendation for your actual weight? It is unusual that the fronts and rears would work out to the same PSI.

Brett Wolfe

Thank you. It is a 1999 Flleetwood Southwind, on a Ford Chassis. The psi on the sidewall is 95. They are new tires that we put on a few months ago. I have not been able to find a place to get the coach weighed around here. It does not have an on-board air system.

[RHeald]

The way I got around this with our previous motorhome was to buy a 5hp compressor mounted on a 20gal tank at Lowes. It was a rebuilt unit so the price was right. I removed the pump from the tank, mounted it to a plate and then mounted it in a side compartment. It was hardwired to the A/C power and plumbed to the tank which I welded tabs to the side of and bolted in between the frame rails under the rig. I had no problems airing up my tires as a 5hp compressor airs up to 120psi, but more importantly I had the CFM to do it in a reasonable time frame as well as being able to run air tools for removing lug nuts on the rig or the toad.

I know this kind of project is beyond what a lot of people want to get into but it was fun to do and if you have the right tools and the do-it-yourself spirit it's not that hard.

The problem with most small portable compressors is that they lack the CFM which is the true measure of how long it will take to air up your tires and it is very misunderstood by consumers. A compressor with 120psi but no CFM will take all day to air up a single RV tire. More importantly compressors with to little CFM will work themselves to death trying to air up an RV tire.

Yeah, that's probably not going to be feasible for me to do, but the CFM is a new term to me. What does CFM stand for, and how much do I need to have to put air in these tires. If you are supposed to check the tire pressure when they are cold, seems to me there should be something that you can carry with you to correct the situation if need be. Is an on-board air system something you can add to the coach? What is the approximate cost?

Thanks,

Kathy

[wolfe10]

The psi on the sidewall is 95. I have not been able to find a place to get the coach weighed around here.

The 95 PSI on the sidewall is the correct pressure IF the tire is carrying its maximum allowable load.

Until you weigh it, another source for PSI is the GVWR tag near the driver's area. It will give PSI for axles loaded to their GAWR (Gross Axle Weight Rating),

And many truck stops, moving companies, grain elevators, etc all allow for axle weighing. But that assumes perfect left/right weight distribution, so individual wheel position weighing is far better. Then, using the heavier wheel position on each axle, go to the tire manufacturer's PSI/weight chart to determine the minimum PSI for all tires on that axle. I recommended adding 5 PSI as a safety margin to that minimum.

Brett Wolfe

[Guest Wayne77590]

Kathy,

I'd like to help you find a scale, but you don't have any information in your profile regarding where you may be staying (living).

As you are traveling down the road, look at the truck stops and those have weight facilities will most likely have a great big yellow and black sign that says, "CAT Scales."

Depending on your location, you may want to check with the local highway patrol to see if they would offer a weigh service on the side of safety. You could make a donation to the State Trooper's Association. They usually have portable scales and may be able to help you.

[NWJeeper]

Yeah, that's probably not going to be feasible for me to do, but the CFM is a new term to me. What does CFM stand for, and how much do I need to have to put air in these tires. If you are supposed to check the tire pressure when they are cold, seems to me there should be something that you can carry with you to correct the situation if need be. Is an on-board air system something you can add to the coach? What is the approximate cost?

Thanks,

Kathy

Kathy, It's not surprising that you haven't heard of CFM as compressor manufacturers don't usually mention it choosing instead to wow consumers with a large PSI rating on the box which doesn't really tell the whole story. Compressors can be made to put out 120psi without much problem but if they don't have the CFM to back them up they won't do much. CFM stands for Cubic Feet per Minute. CFM increases with the horsepower rating of the compressor. Typically electric compressors have around 1.5 CFM per horsepower.

If you were to equate it to electricity, then PSI would equal Voltage, and CFM would equal Amperage. Think of it like trying to plug in to many hair dryers on one circuit, there just isn't enough amperage there to run them all even though you have enough volts and you blow the circuit breaker.

Without enough CFM the compressors will just run and run and run until in burns itself up as it works it's poor little butt off trying to fill that huge tire.

To be able to fill an RV tire and live a long and fruitful life you need a compressor with the largest CFM rating you can afford or fit in your rig. For a small portable type of compressor this won't come cheap. Units are made by Viair for 12 volt use which are small and are meant for permanent mount but their CFM will be low and they are very expensive for what you want to do. For most owners of larger coaches it is just advisable to bring your rig into a local tire shop periodically and have them check the pressure if you don't have access to an appropriate compressor. Even with the Viair you will still need a tank to store air, this is one way to increase CFM with smaller compressors.

Coaches with large tires and needing PSI ratings of upwards of 110PSI just aren't synonymous with small air compressors to get the job done.

Sorry for such a long response, can you tell I used to sell compressors for a living?

An on-board-air system is a possibility if there is enough room to add an engine driven compressor to your engine. We actually do this on our Jeeps for airing up our tires after a day spent on the trail. However we use old air conditioning compressors on the Jeeps. For a coach you would want to use an engine driven compressor from a semi truck or one of the DP coaches. Systems like this also involve the installation of an air tank to keep the run time of the compressor down and not kill it. I do not know if there is anyone out there that does this sort of thing outside of do-it-yourselfers like me. My guess is it would be prohibitively expensive if they do.

[RHeald]

Kathy,

I'd like to help you find a scale, but you don't have any information in your profile regarding where you may be staying (living).

Sorry new to this, don't know how to add that info. I'll keep looking, but I'm in FL. I'll keep an eye out for CAT Scales signs. Thanks, did not know that. I'll call the Highway Patrol and see if they can help me.

[RHeald]

The 95 PSI on the sidewall is the correct pressure IF the tire is carrying its maximum allowable load.

Until you weigh it, another source for PSI is the GVWR tag near the driver's area. It will give PSI for axles loaded to their GAWR (Gross Axle Weight Rating),

Hmmm, I think that sticker says 110 psi. I thought that was for the old tires. Can I put 110 in these tires if the sidewall says 95?

[RHeald]

For most owners of larger coaches it is just advisable to bring your rig into a local tire shop periodically and have them check the pressure if you don't have access to an appropriate compressor.

I do this at the start of every trip and tip the guy that checks the pressure for me. I just don't want to be a bother to them. I am just concerned about them on the road. I read somewhere you were supposed to check the tires every day. Great, but if they need air???? I am so pleased to read all these responses and get all this great information. I really thought it was something I was doing wrong. Nice to know it is the little compressors with not enough CFM, not me. Thank you all so much. I've learned a lot here. Will print and save in my 'book'. I get so much conflicting advice.

[wolfe10]

Hmmm, I think that sticker says 110 psi. I thought that was for the old tires. Can I put 110 in these tires if the sidewall says 95?

OK, if tires are different than those on the GVWR tag, to come up with the recommended PSI based on each axle carrying its GAWR, take that axle weight rating and go to your tire manufacturer's inflation chart for the NEW tires.

For example, if Michelins, go to: http://www.michelinrvtires.com/michelinrv/...tion-tables.jsp

Again, this should be viewed as a TEMPORARY ANSWER until you actually weigh the coach.

Brett Wolfe