From personal experience the further back the axle on a trailer the faster the wear. Look at tri axle equipment trailers for example it always the third axle that wears first BECAUSE the middle and rear axles are pushed and scuff the pavement and stress the sidewalls. Same applies to TTs....rear axle gets more stress and abuse. As for tow vehicle....the best tires should be on the front no matter FWD or RWD to give the steering the best chance wet or dry of gripping the road. Also DOT regs prohibit recaps on the front of commercial trucks...why....lose the tread less control if on the front.