Selecting Larger Wheels and Tires for Tracker Pontoon Boat Trailer

Question:

I have a 1995 Tracker 21foot pontoon boat on a Tracker trailer with 10inch tires and wheels. I want to go to 13inch tires and wheels for more clearance. The pontoon is a 21foot fishin barge but Im not sure about the weight. I want to be sure to have a stout enough load range while going 65 to 70mph. What would be your recommendation? There are no fenders on this trailer. I can send a picture if necessary.

asked by: Mike

Helpful Expert Reply:

You can change to larger tires on your boat trailer so long as you retain adequate clearance. Not having fenders on the trailer makes this easier but you still need to account for the normal vertical travel of the axle/suspension, typically about 3-inches. If the new tire size is wider you need to be sure you still have enough tire-to-frame clearance. The first number in a tire size is the width in millimeters; an ST175/80R13 tire is 175mm wide, or 6.88-inches. A good resource you can refer to is the linked article on tire sizing.

As far as weight load ranges go you'll want to confirm the total weight of the boat/trailer combination so that you can select tires with enough capacity. Take that total boat/trailer weight and divide by the number of tires on the trailer. That gives you the minimum weight carrying capacity you need, but naturally you'll want to select tires to give you a safety margin.

Speed ratings vary by tire size and brand. We will call out a tire's speed rating in our specs if it is anything other than the nominal 65-mph default speed rating. L-rated tires are good to 75-mph; M-rated tires are good to 81-mph.

The linked page shows you all 13-inch trailer wheel/tire items. These are offered in 4-on-4 and 5-on-4-1/2 wheel bolt patterns. Karrier ST175/80R13 Radial Trailer Tire # AM31994 for example is a Load Range D capable of handling 1610-lbs at its rated 65-psi pressure. This tire is rated M for up to 81-mph.

expert reply by: Adam R