Hello Dear,

Heel and toe wear refers to the partial wear of individual tread blocks, appearing as sawtooth wear, but in the direction of tyre rotation instead of across the tread. This wear pattern is most common on non-drive wheels, e.g. the rear wheels of a four-wheel drive vehicle and can be corrected by more frequent tyre rotation.

Causes of heel and toe wear can include rear toe error and soft tyre tread compounds.

for more info:
https://www.mintys.com/heel-toe-wear/

good luck