Burning rubber smell in 4x4

[silvdur]

I have noticed this smell when truck is in 4x4. No odor noticed in 2WD.
I do not hear any belt squeal and this is driving truck on contaminated roadways.
Thoughts?

[rapidoxidationman]

Are all 4 tires the same in pattern and in wear? If one or two aren't, you might be scrubbing them (and wearing hard on your driveline).

[DmaxMaverick]

Could be CV-Joint boots or failed/failing U-Joints. Tire scrub is possible, but usually only noticeable if on dry pavement (when you shouldn't be in 4x4), or hard-pack snow or ice. You can identify the tire scrub possibility by rotating only ONE side. Left OR right. That will balance the roll-out. However, I do not suggest continued driving with this condition once 4x4 is no longer seasonally needed, or you expect extended periods on dry pavement. The scrub condition will worsen the next time, and won't be correctable (new tire time).