Reduce aircraft ground friction

I have downloaded a freeware aircraft that works fine, except that I think it has a too high ground friction. I mean that when I land, the ground speed drops too fast, even though I don't use the brakes. It is the same when taxiing: I need to apply significant power to have the aircraft moving. I think it is not very realistic.Is there an easy way to reduce this ground friction of the aircraft?Is there some part of the air file that I can change with AirEd? Or something I can change in the aircraft.cfg file?Thanks in advance for your help, I am not an aircraft designer at all...Eric