I have found a used compressor that is regulated to 125psi. Its a good quality 2 stage oil filled pump and a 5 hp motor and is about 5 years old. I would really like to use it to fill my motorhome tires and 125 just doesn't get it.

I am thinking I could just switch out the pressure switch for a higher psi (175). What do you think? Would it harm the pump? Pop the tank?

I'd start by looking at the data plate for the maximum pressure of the tank. If you went this route, you'd also likely have to swap out the relief valves... Chances are that the tank isn't rated for that much higher pressure. Could you get away with it? Likely. Are you setting yourself up for risks and problems? More likely...

How much air pressure do motorhome tires take? Over 125 PSI in a tire seems unlikely.

As for the tank, most air recievers are hydro tested to 300 PSI. As said above it should have a data plate somewhere with maximum pressure and miximum working pressure on it. This data was generated when it was new though, so the tank can be in about any condition after 5 years, especially if the PO didn't regularly drain it.

As for maximum pressure that you can run the pump too, it may have trouble with the valves seating if you exceed the recomended pressure, especially if it has reed valves. Depending on the shape of the pump, the excess pressure could be hard on the rings as well.

My compressor is an IR capable of up to 175 psi tank pressure. I run it at 135 psi, I can't see a really good reason to take it up to 175, it is harder on the motor and the pump and I dont have any need for it. Of course, if you put 150 psi in you motor home tires for whatever reason, then you need higher pressure...

Later,
Jason

Cripes, our semi tires never ran that high of pressure. The compressor I'm building is capable of 200 p.s.i., but it's going to run around 140 max, to help it live longer.

High quality 16+ply tires can easily see 125psi COLD then you've got to figure some tires can gain 20-30psi from heat depending on load and other environmentals (bearing/brake heat).

i wouldn't go that high.. i regularly turn compressors up at work zero problems have come from running them ~140. what kind of pressure switch do you have? most, even though some what limited, are adjustable. pic?

most have a spring adjustable switch
all you do is find where the cord runs into the compressor take off the plastic cover and you should see a nut with a spring under it adjust the nut up or down to get the desired air pressure
and needles to say make sure you unplug the unit before working on it adjustment may cause power up

What pressure do motorhome tires run?

What pressure do motorhome tires run?

With a LRG or LRH 19.5" tyre 100-120psi is not uncommon.

The tires are 125 psi. YOu really can't fill a 125psi tire with a compressor at 125. First you have some pressure loss through the hose ( I have a 100' on a reel to get to the MH when its parked across the street) Even if the run was shorter, without a large pressure differential, it would take hours for me to bring all six tires up to max operating pressure. I have a power tank that I have been using, but sometimes it runs out.

Its a moot point now anyways. The compressor is 175 psi. I checked it out and the intial info was wrong. Its an IR rand 4000, model # RA5T80V1, 5hp, 80 gal, 18cfm @ 175psi :eek: It is a 3 phase, but the has a converter on it already. I have found out that I will loose about 20% performance due to the converter. Oh well, I can live with that. It also came with a water seperator.

I got it home today. These things are kinda top heavy :D. Its a huge behemoth. The wife about crapped when she saw it. She was worried it was going to shake the house. She couldn't believe how quite it was compared to the Craftsman it is replacing.

I have searched all over the net,but can't find any info on this compressor. I get one hit from a machinery dealer trying to sell one for $1500. Anyone know anything more about this model? I would love to find a manual on it. Nothing on the IR site either.

I bought one at an auction a few months ago, it was a Ajax Air branded unit, w/ a IR pump. Model number is aj5t80v1. Sounds like the same pump. I think the prefix on the model number just designated what company the pump was for. I could not find any info on mine after I bought it either, however, I came to find out later that IR used different model numbers for their private labeled compressors, than they do for their main stream models. If you place a call to IR, and wade through their unbelievably poor customer service, you should be able to get instruction manuals and whatever information you might want...

Later,
Jason

Here is the link to the manual I downloaded from their website. The manual is for their 15T model, but I suspect the 5T is the same pump. Anyhow, I wouldn't order parts for the 15T expecting them to work on this pump, but the manual seems fairly accurate, at least to what my machine is.

Clicky (http://www.irservicenet.com//filestorage/SCD%2D838A%5F%2Epdf)

Later,
Jason

Thanks Jason. I was looking at yours last night and noticed that the pump looked exactly like mine. Thanks for the link.