8" to 12" trailer tires

Hi All,

Is it worthwhile to exchange 8" trailer tires to a 12"? I was given a trailer with decent 8" tires (the tread looked decent), but was wondering if I should spend the extra $80 on 2 12" tires.

I'm only driving between 1-3 hr. each way to the dirt at 60-65 mph. I know I should be going 55 but.... Will the 8" tires be able to handle the speed? Also, where do I find out about speed ratings on trailer tires?

Thanks for your thoughts.

Hi paull

Do you carry a spare tire for the trailer? If not the 12 inchers would be a good choice. Also do you drag the trailer across any rough dirt? The bigger the tire the better it rolls over big holes and bumps. I know if I was towing I would not want to leave the trailer and bikes by the road to go get a tire repair or drag it in flat! The 12 inch tires take less abuse on an off road


You need to post ALL the numbers and leters off the side of the tires on here.

We have tire guys.

Bronco has forgotten more about tires than most men will ever know.

You can buy good 8" tires but I would be more concerned about the wheel bearings. I would make the switch.

Trailer came with a new spare so that's cool. I will post numbers to Bronco when I'm home on Wed.

Regardless of whether I go with the 8 or 12", I'm still using the same wheel bearings so what difference does that make?

When I do grease the bearings, what is the process. Is it just like a motorcycle wheel, do I need a punch to pop out the bearings. Will I need new seals, etc or can I reuse?

Also, can I use the Belray Waterproof grease to lube the bearings?



I personally dont like the little wheels when im on the highway so I put a larger axle and 14 in rims (with new tires) on our trailer awhile back. The trailor rides alot better at speed and dosent worry my on the highway any more. A little more expensive route to take, but I dont regret it one bit.

I did the 8" to 12" swap just to slow the wheel bearings down.

It is cheap and has lots of value.


12" without a question

8" and 12" tires are crappy at best.

by virtue of the larger size and more air volume the 12 " tire will have a higher load capacity.

much less heat build up on a 12" because it is turning slower

better tire life

more safety margin

60 mph = 88 ft/s

12" wheels would be spinning at 28 revolutions per second


8" wheels would be spinning at 42 revolutions per second

I assume they are 12" rims and 8" rims so the rpms will be a little lower since this is not taking into account the diameter of the tire but you get the idea.

The main thing is to check and make sure the bearings can handle extended high rpm. Otherwise, you'll trash the bearings.

How do I check to make sure the bearings can handle the rpms? It's an older used, 4x8 trailer that was used to tow dirtbikes.

I do plan on regreasing the bearings. I just wondered if it was worthwhile to change to 12" tires. Sounds like it is a good idea to do so.

Thanks everyone.


I had a trailer recently wtih teh 8 in wheels. It survived at least 4 trip journeys of 800 miles each way, extended high speeds (60-65 mph) with not a problem. I had my Triumph Daytona loaded on it and other crap strapped. Halfway through the 5th 800 mile journey I stopped at a gas station and pulled out to find my right wheel bearing had locked up, and disentegrated! Luckily I had all my tools with me and was able to repair it with the help of a bearing at the only Ace hardware in town, using my electric grinder to remove the bearing race that had welded itself to the axle. An hour later and I was on my way. Too bad the trailer was stolen from a locked location a week later.

I recommend going to the 12 inchers to save bearings in the long run.

When I bought my trailer the 12" wheels were not interchangable with the 8" hubs. At northern tools locally the tires wheels and hubs were cheap enough to swap out!

The 8" were 4 lug and the 12" were 5 lug.



Hubs: http://www.northerntool.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=6970&productId=23655&R=23655

you can get 12" wheels with a 4 lug. Even better is goto Northern Tool and get 13" wheels with a 4 lug that will fit on this same trailer, you just need to modify the fenders. Less wear and tear on the bearings. The 12" wheels are also very narrow coming in around 5".

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