They are OK. We used a few in a custom product for a customer. They take about 5 minutes to get a 5 gallon tank up to 100psi. They get hot as heck and make a fair amount of noise, but seem to keep working. If the tank is already pumped up, you will be fine airing up a set of 35's, but starting from scratch with no tank, it can take a few minutes. It beats the heck out of no pump or one of the cheap walmart units, but for the money, I might thing of either doing an OBA or a CO2 setup.