Comparing ST175/80D13 Bias Ply Tires to ST175/80R13 Radial Trailer Tires

Question

Question:

My trailer came with ST175/80D13 tires on 4 1/2inch 5 lug rims. Can I replace those with a ST175/80R13 tire? Looks like the D tires have a much lower load rating.

asked by: Matt

0

Expert Reply:

The primary difference between special trailer tires ST175/80D13 and ST175/80R13 is the type of construction.

The D in the first tire size indicates bias play construction as with wheel/tire # AM3S050. For the other tire designation ST175/80R13 the R indicates radial construction. The main practical difference between the tire types is that bias ply tires have stiffer sidewalls that make them better suited to rough roads and off-road use while radials have more flexible sidewalls that give them better traction and cornering for highway use.

Either tire type will be available in various weight load ranges. These load ranges are also designated by a letter code. In the bias ply type we have Load Ranges B, C and D and within the radial tire category we offer Load Ranges C and D. All tires in this size appear on the linked page, both bias ply and radials, and all available load ranges. Trailer tires also come with varying speed ratings (yet another letter code!) such as L (good to 75-mph) and M (good to 81-mph).

The right tires for your trailer will have both weight and speed ratings that match or exceed your actual driving requirements. For load range select tires that meet or exceed the trailer GVWR; for example, if a single axle trailer GVWR is 2500-lbs then using two of Kenda wheel/tire # AM31985 which is good for 1610-lbs each will mean that the total tire capacity is 3220-lbs (2 x 1610) and so these tires on such as trailer would give you a weight safety margin of 720-lbs (3220 - 2500 = 720).

expert reply by: Adam R

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Answer 1

If the total weight of your pop up camper is 3,300 lbs then you would need a wheel/tire combo that at least has the capacity of 1,650 lbs. The closest tire we have to that capacity in your size is the part #AM10210 which has a 1,610 lbs at 65 psi…

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Answer 2

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 3

The difference between an load range C and load range D tire in the same size is the capacity and psi rating. The two tires will still have the same dimensions and fit on the same wheel. The D rated tire has a higher capacity. For a ST175/80D13 like…

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Answer 4

Load range B trailer tires are going to have a lower capacity than C load range tires. Basically that, psi rating, and the ply rating are the only differences. A higher load range tire would last a little longer than lower load ranges of the same…

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Answer 5

The three most common lug stud sizes for a trailer are 1/2"-20, 9/16"-18, and 5/8"-18. In order to make sure you get the correct lug nuts you need to measure the lug studs on the trailer now as we have no way to look this up for…

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Answer 6

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 7

Your math is correct in your trailer weight load example. If a fully-loaded tandem axle trailer weighs 4000-lbs then each of the 4 tires will bear 1/4th of that load, or 1000-lbs. In this case a tire rated for 1300-lbs would provide a good safety…

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Answer 8

To determine the size of the hub assembly you need to purchase you have to determine which bearings are in the old assembly. If the old assembly has L44649 inner bearings, you would use the hub you chose #8-258-5UC1. If the inner bearings are marked…

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Answer 9

To find the load capacity for your axle you should look on the trailer VIN plate or sticker that lists the VIN number. The weight rating of the axle should be listed on that same plate or sticker. Also, the axle could have a tag or plate on it that…

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Answer 10

Even though I cannot comment specifically on the grease you used because I am not familiar with it, I can tell you the best grease for trailer bearings is a a grease with a rating of GC-LB, which just means it is made to withstand very high…

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Answer 11

To determine the size of the brake assemblies you need you have to measure the depth and width of the hub drum on the axle like what you see in the picture I attached. The most common size is 2-1/4 inch wide like the #T4071600-500 that you…

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Answer 12

You can add larger wheels and tires to a trailer as long as you have enough room for the larger size. The main clearance issues we find when putting larger tires and wheels on a trailer is from the top of the tire to the fender and from the inside…

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