What Tire Pressure Is Recommended On 4.80/4.00-8 Load Range C Trailer Tire For Highway Speeds

Question

Question:

I just bought this boat and trailer 14 alum Grumman / galv trailer Tires are 4.80-4.00-8 K371-006 Max rating 90 psi 745 lbs What tire pressure should I run for highway driving? 90 psi seems like a lot. Thanks!!

asked by: Greg

0

Expert Reply:

The tires should be inflated to 90 psi on the highway as well as other roads, regardless of load size. The problem is that under inflating a trailer tire will lead to degradation of the tire.

On trailer tires, the side walls are thicker than on car tires so they can handle more vertical load. An under inflated tire side wall will heat up more often and quicker and will lead to early wear and possible failure of the tire. The best thing to do is to follow the rating on the tires and inflate them to the maximum recommended psi. Also, trailer tires are speed rated for 65 miles per hour maximum.

i have incldued a link to our tire FAQ article for you.

expert reply by: Michael H

0

Thomas S.

6/17/2020

I have a set of carlisle 4.80-8 2 ply load range b on my trailer that I tow behind my motorcycle and am wondering what should the air pressure be. The trailer empty weighs 100 pounds and the max would be 300 pounds so right now I get a lot of bounce and only see about 2 inches of the center tread making contact with the pavement if even that amount and by the way this trailer is about 30 inches wide. Can you help me out here?

Chris R.

6/22/2020

For that size tire in a Load Range B you're looking at a max psi of 60. I really can't recommend inflating them to less than this because it would essentially lower their capacity to an unknown number. Is there any way to add some more weight/cargo to the trailer?

Thomas S.

6/22/2020

@ChrisR The trailer is being towed behind a motorcycle and it would be better on the motorcycle with the lightest weight possible. The trailer weighs 100# and I'll be putting in a 5 gallon gas can, 5 gallon water can, and standard camping gear so I don't see it topping 250 lbs. The other choice was strapping all this to the bike or using the trailer and since my bike is a modified 1950 Harley I want to carry spare parts and tools. lol

Willie

1/9/2026

There is a minimum tire pressure spec for 4.80x8 tires and its 10-15psi based on its ply rating. This is an ST tire specification that specifically targets "very light trailers". There are online calculators that can help you calculate the mathematical ideal pressure, but the min pressure is 10-15psi. All these people telling everyone on the internet to "inflate to the max psi" are just saying the safe answer for the 99% of people who cant do the measurements and math to calculate the RIGHT psi for their specific trailer, tire, temperature and load - because overinflation is safer than under-inflation. However there are cases - such as yours, where a specific pressure needs to be calculated and utilized for the proper operation of the tire on the trailer... just keep it above the minimum and monitor for for excessive heat. Also remember using this specific and low of a pressure means it will have to be checked and adjusted MUCH more frequently - even day to night if there is a significant change in the ambient temperature. Over-inflating the tires washes away most of these variables and that's why doing so it recommended for the general public

Answer 1

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 2

We have exactly what you're looking for with the Taskmaster 4.80R12 Radial Trailer Tire #TT48012C. This has a load range of C (990 lbs at 90 psi) and a speed rate M which is 81 mph. If you're wanting/needing to replace your wheels as well you…

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Answer 3

For smaller tire sizes like the 4.80-8 that you mentioned the highest speed rating we have is 65 mph like the part #AM10002. This is in part due to the smaller diameter of the tire which means it will be spinning more revolutions at the same speed as…

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Answer 4

The reason that you cannot find a list of all load ranges and the weight capacity for each in regards to trailer tires is because it will be different for each size. For example, a 205/75-15 tire like part #AM10245 which has a load range D rating is…

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Answer 5

The Load Ranges for trailer tires basically dictate the weight capacity range of the tire. I don't know what size you have, but there would be no reason you couldn't go from a Load Range B tire up to a Load Range C. I attached a couple help…

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Answer 6

Hey Steve, I can't seem to find anything with that pattern that didn't come up as a damaged wheel where the bolt holes were damaged, throwing off the measurement. Are the bolt holes on your wheel worn/oblong? With you being at 4-7/8"…

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Answer 7

Currently the only hub we carry that uses the Inner Bearing #LM67048 and Outer Bearing #LM11949 is the Trailer Hub Assembly #AH15450ECOMP. This is a idler hub that is to be used on 3,000lb axles. It has a 4 on 5" bolt pattern and uses threaded…

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Answer 8

Sounds like you're needing the Redline Grease Seal #SL150. This has an ID of 1.5" and an OD of 2.332" like what you're needing. If your bearings are toast, then you'll want to replace those too. If you can get me part numbers or…

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Answer 9

Hi. The correct tire pressure for a 4.80-8 for a load range B tire with maximum load at 60 psi, such as the Kenda #AM10002, would be 60 psi. You want to keep your tires inflated to the maximum air pressure; they will wear less, perform better and…

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Answer 10

Hello Steven, thanks for reaching out. We do offer a few bearings with a 1.25" ID but sadly there are no hubs made for a 1.25" straight spindle. A lot of older trailers use bearing combinations or hubs that are now obsolete, and it sounds…

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Answer 11

The proper amount of pressure in a 4.80/4.00-8 load range B tire would be 60 psi. This should be listed somewhere on the sidewall of the tire. Unlike passenger car tires, trailer tires should be kept inflated to the maximum pressure as stated on the…

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Answer 12

The psi of your trailer tires will be listed on the side wall. It will list the max psi which is what you will want to fill them to regardless of how much weight you have. For reference, the 4.80 x 12 tires we carry have a 60 psi max for load range B…

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What Tire Pressure Is Recommended On 4.80/4.00-8 Load Range C Trailer Tire For Highway Speeds

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