Changing Out 4.80-4.00-8 Tire Size on Boat Trailer With Larger Tire Size

Question:

can i increase from a 4.80/4.00-8 tire to a bigger size tire on my boat trailer

asked by: Fran

Expert Reply:

You can go larger in tire in some instances, but it's going to depend on how much larger you want to go. You don't want to see any less than 3 inches of clearance between the top of the tire and the underside of the fender. A 4.80/4.00-8 tire is usually about 16 inches in diameter when fully inflated.

A 5.70-8 tire would be about 18 inches in diameter, which would provide about another 1 inch of trailer deck height. This is the largest tire we offer that will fit on an 8 inch rim.

If you were looking to go with a larger diameter wheel, you'll need to go with a wheel that uses the same bolt pattern as your existing wheel. Tires meant for a 10 inch wheel would all likely be too wide for your trailer, so the next largest tire size would be 4.80-12.

Going with a larger wheel size would likely mean replacing your existing fenders, or at least raising them to provide the proper clearance. A 4.80-12 wheel/tire combo like # AM30620 would provide a 4 on 4 bolt pattern on a 20.7 inch diameter tire. If your current wheel bolt pattern is 5 on 4-1/2 inches, you could use part # AM30660. I'll link you to an FAQ article that shows how to determine your wheel bolt pattern.

expert reply by: Mike L