If you get stuck in mud or snow slip a shingle under the wheels for extra traction.
Shingles are a great idea but so is cat litter or big sacks of sand.
The extra weight adds traction. You get them professionally cleaned time to time which works fine, except you notice edges getting darker and darker that doesn't get clean when the carpet guy comes. The problem is dirt getting into your carpets from below, through tiny cracks and open seams under your carpets where walls meet floors and on stairs. Over the years air passing through leaves dirt on your carpet like a filter. Next time you carpet, seal all open cracks and seams with a good bead of caulk before new carpet is installed to keep it looking great.