Changing tire size Attn: Capt Fred

[Bluefish]

I just got and old trailer from a friend of mine and I am setting it up for my boat after launching it for the season I want to put new tires and rims on it. Right now it has B78-13ST tires 5-41/2 dia rims I would like to change them to a 14” tire and the rims seem to still come with 5 bolt 41/2 dia measurement. I want to increase the tire size for the extra load rating of about 4or5 hundred pounds. There does not seem to be a clearance problem in changing size does any one know of any problems this might cause? <br />Thanks

 

[fsherrerd]

Re: Changing tire size Attn: Capt Fred

Changing to a different tire size which may have a larger carrying capacity does not mean you can actually carry more weight. In addition to tires, the axle and springs are designed to carry a certain amount of weight, as tated on your trailers vehicle identification plate. Most reputable manufacturers match the springs with the rated capacity of the trailer in order to provide a smooth ride. They won't use use heavier springs than are to meet the GVWR because they will not allow for proper spring travel which results in a rough ride and shock transmission through the boat. Additionally the axle and spindle are matched for the original capacity. If the "old" configuration of your trailer with the 13" tires and wheels is matched correctly, the axle and springs are only rated for that type of overall GVWR which ultimately determines your capacity.

 

[Bluefish]

Re: Changing tire size Attn: Capt Fred

Capt Fred Thank you for your informed reply I do see the problems that would arise if I was trying to raise the GVWR. But I was thinking of going to a 14” tire only for extra safety since I have to buy new ones anyway, I am 100# under the GVWR rating also this is a tandem wheel setup any other thoughts? <br />Thanks

 

[fsherrerd]

Re: Changing tire size Attn: Capt Fred

While you may visually see no clearance issues, you need to account for the full distance the springs travel when providing the designed suspension for the trailer. If you are only 100 pounds below the traler GVWR, the larger tires may give you more potential capacity (GAWR), but you are still left with the same true carrying capacity based on the manufacturer matching the springs and axles to the stated GVWR.