We are sorry to hear you are having challenges with your Exmark Navigator. Aside from putting more air in the tires, you can also try not filling the collection tub as full. Our Navigators will pack a lot of grass in the hopper putting additional weight on the tires. If you continue to leave marks once you start mowing again in the spring, please send us your contact information to email@example.com
and we will have one of our engineers contact you to work through some possible solutions.