Dogs peeing on tires is a learned trait that goes back millenia. Peeing on something is a signal to other animals that this is a dogs territory and further communicates this quite effectively to other animals thru urination exchanges.
As far as tires go this is the equivalent of sending a postcard or email or text to another dog that says - Hey! I’m smelling you! Reply immediately upon receipt.
I am certain that you could find historical references for dogs pissing on royal coaches wheels throughout known history.
Growing up in a rural area I have observed this my entire life and to the extreme. As after one ‘trained’ dog will pee on your tires/rims all others will follow suit - inviting others to reciprocate in the communication and ‘training’ others to do so even if your tires are are not marked. Soon your tires and wheels will be marked with sticky pee and coated with dust. Even if you wash the pee off dogs can smell the residual and reciprocate. Therefore the only solution is a solution:
Solution: If you Bleach your tires and rims frequently this will reduce the problem - However not entirely, ‘Trained’ dogs will pee as their nature instructs them and pee on tires instinctively thereby repeating the cycle.
IF you recognize the repeet (sic-yik) offenders yell, scream, curse, spray them with a hose of water or your own urine (very very good repellent) until they quit. They Will learn to go elsewhere.
I have spent Way too much time explaining this but I hope it helps multitudes.
Later,
Bcudamatt