I use the Smittybilts 5.4 cfm 12v pump, it airs up my 33's from 8 psi to my 25 psi street pressure, all four, in about 15 minutes including set-up. I was going to set up an onboard air before I won this in a raffle. Now that I've used this I'd buy one of these in a heartbeat. Some of the guys in my club have used it on their 35's and were amazed at the fill rate. I'm happy. 
Mine is the model below it with a 2.54 CFM, I think. I think I could get my 35s close to 25 psi in about 20 minutes. I have not been motivated to do more than the single time trial of 10 psi to 40 psi on the gage (seems to be 34-35 psi on my accurate gage). I might get bored at some point and try a fill based on time rather than gage pressure. See what 3 minutes can get me.
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1989 4Runner: Dual Ultimate (Inchworm front & Marlin 4.70 rear), Marlin Twin Stick, 1200-lb clutch, 4.88 R&P, Aussie Front, Detroit rear, 30-spline Longs, Long hub gears, ARP hub and knuckle studs & 35x12.50 Cooper STT PRO tires. Marlin rear bumper & sliders. FROR front bumper. SAS with Alcan springs & Rancho 9000XL shocks. Budbuilt Bolt-on traction bar. Custom Interior Cage by Those Guys Rod and Customs.
Moab Tested & Rubicon Approved
