Switching to Smaller Trailer Tires on Robalo Boat Trailer for Better Garage Clearance

Question:

I have a Robalo 180 boat trailer single axle with brakes on it. The tire size is 205/75 R15 tire size. I’m looking to lower the trailer a couple of inches to get into a garage. Will a 145/R12 E rating wheel fit on the trailer with breaks and be used for local transport ??? It will save me about 3 inches. Thank you.

asked by: David S

Expert Reply:

The overall diameter of an inflated ST205/75R15 trailer tire is just over 27-inches. The size ST145/80-12 has an overall inflated diameter of just over 21-inches. Switching between the two would give you a height drop of half this difference, about 3-inches as you noted.

An E-rated tire in size ST145/80-12 will offer a weight capacity of 1520-lbs, such as Kenda # AM31215, which mates this tire size with a 5-on-4-1/2 bolt pattern aluminum wheel. As long as your hubs have this same bolt pattern you can make the swap. Just be sure that your loaded trailer weight is within the combined capacity of two of these wheel/tire items, which is 2 x 1520-lbs or 3040-lbs.

expert reply by: Adam R