Changing from a ST205/75D15 Tire and Wheel to a ST205/75D14 Tire and Wheel on a Trailer

Updated 04/15/2020 | Published 02/07/2013

Question:

I have a 6x12 enclosed wells cargo trailer and need new tires. What are the effects of me changing from st205/75d15 tire and rim to a st205/75d14 tire and rim. I presently have a 14 inch avaliable for a spare. I found both tires on your site just checking to see if it really made a difference. if i need to i will buy a 15 inch. Thanks

asked by: Randy K

Expert Reply:

The main factors that you will want to take into consideration when moving from a st205/75d15 tire and wheel to a st205/75d14 tire and wheel is the weight capacity of the smaller tire and wheel and the bolt pattern.

The weight capacity of a trailer tire is divided into load ranges, B, C, D, E, or F, however, tires with the same load range will have different weight capacities for different size wheels. For example, a load range C tire for a st205/75d15 tire and wheel will have a weight capacity of 1,820 lbs at 50 psi and a load range C tire for a st205/75d14 tire and wheel will have a weight capacity of 1,760 lbs at 50 psi.

At this time we do not carry a st205/75d14 tire and wheel that can match the weight rating of a load range C st205/75d15 tire and wheel, but a load range C st205/75d14 would still be compatible with a 3,500 lb axle.

You will want to verify the weight capacity of your axle and make sure that you choose two st205/75d14 tire and wheel combinations that will be equal to or greater than the weight capacity of your axle.

Another factor to consider is the bolt pattern. Most 14 inch wheels have a 5 on 4-1/2 inch bolt pattern, but 15 inch wheels can come with a few different bolt patterns. I have attached a link to an FAQ article on how to determine your bolt pattern. You will want to verify that the bolt pattern of the 14 inch wheels you are looking at match the bolt pattern of your 15 inch wheels.

expert reply by: John H

Zack

4/13/2020

I had a bead leak on a st205/75d14 so i managed to get the tire off the rim by hand for cleaning and bead sealer but now it will NOT go back on.. measured and the rim is over 16” lip to lip with a 15” bead diameter.. is this normal for a combo rim/tire? And how does a bead leak when the tire is clean and newish while being stretched an entire inch when the bead is seated.. also betting factory had to have used ky jelly and 150psi to get it seated in first place... feel defeated...

Chris R.

4/15/2020

It sounds like the wheel might be a bit too large. Typically a 14" wheel would measure 15" lip to lip with a 14" inside diameter. When a tire is mounted onto the correct size wheel, the bead is pushed down on one side so it goes below the drop seat on the width of the wheel, allowing the tire to install on the wheel without a lot of stretching. The bead could have been torn upon mounting. At this point my best recommendation is to take it up to a local tire shop to have them take a look.