Using 3dsmax 2011, I convert a track of rFactor1. A car floats in the air even if I put AIW which I made at the time of rFactor1. Probably the size of the tree is the size of the original course and thinks that others become small. Is it necessary to change some setting?
I'm guessing your units are set up incorrectly in 3ds Max. Make sure 1 unit = 1m in the Customize > Units Setup, then export the entire track again.