front tires leaving marks

Any input to help prevent my Toro SS 4260 stop leaving tire tracks on long straight stretches of mowing ? Seems to be just the front castor tires.



Front tires are pretty skinny, but air pressure is set to mfg spec of 22 psi. (cold)..



Couple days you don't see the tracks, but wondered if there was anything I could do to help improve this ?



Thanks in Advance, Buddy