Burned rubber smell!!!

When I turn off my tucson, you can see the smell of burnt rubber, not always and also under different conditions. In most cases where I noticed the smell, I didn’t drive too fast or with high load, like trailer operation. Today I was only with my daughter at the doctor in the neighboring town, when I drove my tucson into the garage, smelled like As in the cases before, I looked at everything, engine compartment, wheels, brakes, underbody, wire harnesses in the visible area, exhaust system etc., I could not find out where the smell comes from. It can almost not be due to overheating, because I noticed the smell in the summer at over 30° or as today at -11°. To my Tucson, 2.0 CRDi Built. 2009, 150 HP 4WD, he has now driven about 43000 km mileage, always gentle, no gelling Does anyone of you have the same problems or suggestions about what it can be or what can be the cause??? Thank you for your support. MfG Gerd