By Roger Marble
Here are some things to consider before purchasing an air compressor for your RV.
Look for maximum pressure capability
When making a purchase decision for an air compressor, the number one feature to consider is the maximum pressure capability. You must be able to get up to the max for your tires. You can learn that number by simply reading the sidewall of your tires.
All tires will have a statement that reads something like “65 psi (450kPa) air pressure Max load 2,500 lbs (1,135 Kg)”. That tire is telling you the MINIMUM pressure needed to support the stated MAX load for that tire.
RV trailers usually come with Load Range C (50 psi) to LR-E (80 psi) tires. Some large Class A motorhomes may say 100 psi, but there are a few tires that have higher inflation pressure associated with the max load.
Whatever the highest inflation number on any of your tires, you need to have a bit more capability. I suggest at least +10 psi with +30 psi being desirable. The reason for the extra is that if you need 80 psi in your tire and the compressor is only rated for 80 psi, you may never actually get to 80 because the rate of inflation slows down for all compressors as you approach their upper rating.
Then consider the rate of inflation
The second number to consider before purchasing an air compressor is the rate of inflation, which will be something like 1.5 CFM (Cubic Feet per Minute) @ 100 psi, or maybe 3.0 CFM @ 50 psi. Now you need to pay attention to the “at” number because all compressors will put out more air volume at lower pressure but that 3.0 CFM @ 50 psi unit may only be capable of 0.1 CFM @ 100 psi – which means if you are inflating to 105 it might take you a long time (20 minutes?). Some compressors may mislead you with high a CFM number but state it at a low inflation number – so read the fine print.
Don’t buy more than you need
Finally, do not “over-buy,” i.e., buy more capability than you need. If you do, you may be wasting money on the purchase and also end up with a physically larger and heavier compressor than you realistically need.
Hopefully you will only need to “top off” a tire by adding 5 psi. If you need to add more than 20% of the goal inflation you may have a problem, because if a tire has lost 20% of its air and it was driven there may be damage to the tire structure. Reinflating a tire that has been damaged could result in a tire explosion. If you need that much air, I strongly recommend you call a professional. They should have the training and tools that might even include a “safety cage” designed to prevent injury.