Had the same issue with my Ranger Z520. Tried 4 of the cheaper wheel dollies from Northern Tool, no dice, couldn't budge it. Talked to the Go Jak folks and was advised to buy 4 of their units, cost $1200.00. Found a refurbished Trailer Valet unit on Ebay for $ 600.00. It gets the job done unless it's raining, wheels spin. They offer stand alone and trailer bolt on units, may want to take a look at the Etrailer website. Good luck.