Downsizing Trailer Wheel and Tire Combination to Lower Personal Water Craft PWC Trailer Height

Published 09/21/2016

Products Featured in This Question

Kenda 5.70-8 Bias Trailer Tire with 8" White Wheel - 5 on 4-1/2 - Load Range D

(7487)

$66.96

Brophy Ball Mount for 2" Hitches - 3/4" Rise, 2" Drop - 13-1/4" Long - 10K

(282)

$81.53

Question:

I have a small PWC on a trailer currently sporting very old 4.80-12 5 Lugs. I would like a slightly shorter wheel and tire combo to make loading and unloading easier. I see that your 5.70-8 is a little under 2.5inch shorter, this would give me about a 1.2inch at the wheels and a 2.5inch at the rear of the trailer. Could this be a viable replacement size? What would be the benefits or drawbacks of an 8inch rim vs the 12inch rim. How would more rubber affect the handling? Thank you for your time.

asked by: Travis

Expert Reply:

The 5.70-8 could be a viable replacement size for your PWC, but I also have another solution that may work to make loading and unloading easier.

The benefits of downsizing your tire and wheels are mainly the height loading aspect. With your current setup you have an outer diameter of 20.5 and the down sized tire is 18.1 inches. You may also see some ride stability because the center of gravity will be lower so you may get less sway when towing. Some drawbacks of downsizing your tires are clearance, weight capacity capabilities, and heat build up (the number one destroyer of tires). As long as you keep the tire inflated to it's max psi and do not exceed 65 mph you should not have to worry about heat buildup.

Depending on the current Load Range you have you will want to make sure that you get the correct equivalent or higher weight rated tire. For example if your PWC plus trailer weighs 1,900lbs and you currently have a 4.80-12 Load Range C which is rated at 990lbs per tire at 90psi you will need to get the 5.70-8 Load Range D rated at 1,075lbs per tire at 100psi to carry the weight of your setup, because the Load Range C will have a max weight of 1,820lbs at 75psi.

You will also want to be sure that you choose a wheel that matches the bolt pattern of your hub. I would guess that your bolt pattern is 5 on 4-1/2 inches, but it is important that you measure to be sure. See attached Help Article. For a 5 on 4-1/2 inch bolt pattern 5.70-8 Load Range D # AM30155.

The smaller tire is going to have a difference in width and you would have to measure the distance from the back of the tire to the nearest part of the trailer. The # AM30155 has a section width of 5.8 inches.

An alternative solution to prevent the vehicle from having to go into the water further is a longer ball mount like # BM20. This ball mount measures 13-1/4 inches from the center of the hitch pin hole to the center of the ball hole and it fits a 2 inch receiver. You will still be backing the trailer far into the water but the vehicle will not have to go in as far.

I have linked the above mentioned products and the 5 on 4-1/2 5.70-8 sized tires to this page for your convenience.