8" WHEELS & TIRES WHO RUNS THEM? FAIL OVER 55MPH?

[KIDZAGN]

I wanted to use a wheel under design, but the mgr at a HF store told me the 8" config was only designed for in town use, under 55 mph. He advised even if I could locate tires rated for 80mph plus the bearings might not
hold up on hwy use. In the hall of fame I see many 8" wheel& tire units, I know they are not camping in town or
holding up traffic on the highway. HELP! What mods are you doing th make your 8" units roadworthy.

Mike

Wichita

[bobhenry]

I wanted to use a wheel under design, but the mgr at a HF store told me the 8" config was only designed for in town use, under 55 mph. He advised even if I could locate tires rated for 80mph plus the bearings might not
hold up on hwy use. In the hall of fame I see many 8" wheel& tire units, I know they are not camping in town or
holding up traffic on the highway. HELP! What mods are you doing th make your 8" units roadworthy.

Mike

Wichita

Duh! They put the same bearings in ALL of their trailers. Are you sure this 8th grade drop out REALLY knew what he was talking about.

My 40 x 48 mini HF trailer came with 12" tires while my used 4' x 8' HF had 8's on it. I have swapped hubs tires and all from one trailer to the other. I often on long trips Take a hub from the trailer staying at home "Just in case" and have yet to need it five seasons and counting.

Warning warning warning... The HF hubs come packed with shipping anti rust GLOP this is NOT a hi temp bearing grease. Hell its not even a good grease so remove this garbage completly, then solvent clean the bearings, hub cavities, et all. Dry and repack the bearings and add a golfball sized blop of extra grease in the cavity ( do not fill it)

P.S. I don't tow at 80 MPH either !

[Nobody]

I've been towing trailers of one kind or another for more'n 50yrs. Many with 8" wheels/tires. How many pop-up type trailers do you see on the highways, lots of 'em with 8" wheels? I owned a 1976 Starcraft 'Super Star' pop-up trailer (a pretty heavy pop-up) from 1976-early 80's & towed it many thousands of miles, most at highway speeds with nary a problem with bearings, wheels, or tires. I've owned several small boat trailers with 8" wheels that regularly get 'dunked' while launching at lakes/rivers all over Arkansas, Missouri, Oklahoma, & Texas. Again no problems with regular bearing maintenance (annual re-pack, service). My TD is built on a 1740# HF trailer with 10" tires/wheels (another 'too small' item to many folks) & has more'n 12K miles & 6yrs with no axle/bearing problems. As Bob said above, with any foreign built trailer whether already assembled or a kit, clean the hubs/bearings thoroughly & pack bearings with a good quality, hi-temp grease, check your hubs frequently after being on the road for a while, & you'll find the small wheels will give good, reliable service as long as you want. Key is doing your preventative maintenance being prepared (I have a complete set of bearings/seals for one hub that I carry in Ziplok bag - have never had to use it). My younger son has a NAPA parts store & tells me that over 90% of on-the-road bearing/axle failures he sees can be traced to extreme overloads and/or poor/no maintenance of the 'rolling' components, regardless of wheel/hub/bearing size.

[angib]

100mph on an 8" wheel is 1900 rpm. Whoever heard of a ball bearing that couldn't do 1900 rpm?

[linuxmanxxx]

The majority of the failures on 8" and 10" and 12" tires are the tires and not anything to do with the bearings. Most of the tires are very cheap chinese variaties and are prone to blowouts and throwing rubber. Finding a quality tire in those sizes is quite the task indeed. I would say if you have a 10 or 12 to yank the fenders and upgrade to 13s at the least which are a plentiful tire to find with much higher quality but if not make sure they stay inflated to the pressures the tire calls for as they usually take very high psi and will fail if run at lower pressures. The 12" 4.80 call for 90psi.

[aggie79]

100mph on an 8" wheel is 1900 rpm. Whoever heard of a ball bearing that couldn't do 1900 rpm?

Let's see. That would be 100 mph divided by...carry the...hmmm.

Andrew, I'll take your word for it.

[LDK]

100mph on an 8" wheel is 1900 rpm. Whoever heard of a ball bearing that couldn't do 1900 rpm?

Let's see. That would be 100 mph divided by...carry the...hmmm.

Andrew, I'll take your word for it.

Andrew I'm sure you're right but can we see your formula for figuring that out? Might come in useful someday.

[john]

Let's start with pi(1/2 d)

3.1416(4) - But if the wheel is 8", the wheel with the tire included is larger than 8".

3.1416(8) - My 8" wheel is actually 16" with the tire included. Thus the radius for my 8" wheel is 8".

25.13" Let's call that 24" or 2 feet per revolution.

One mile is 5280'.

That makes 2640 rotations/mile.

Or 158400 revolutions per hour at 60mph.

Now divide that by 60 to convert to hour to minute...

2640 RPM.


Hmm... My number doesn't match (parallel) Andrew's.
What did I do wrong?

[LDK]

Maybe we should get Stephen Hawking to figure it out. I use to be decent at math in school but thats been 32+ years ago.
The old saying is true. If you don't use it, you'll lose it.

[emiller]

It would depend on weight and road and weather conditions. Just be safe.

[Corwin C]

Let's start with pi(1/2 d)

3.1416(4) - But if the wheel is 8", the wheel with the tire included is larger than 8".

3.1416(8) - My 8" wheel is actually 16" with the tire included. Thus the radius for my 8" wheel is 8".

25.13" Let's call that 24" or 2 feet per revolution.

One mile is 5280'.

That makes 2640 rotations/mile.

Or 158400 revolutions per hour at 60mph.

Now divide that by 60 to convert to hour to minute...

2640 RPM.


Hmm... My number doesn't match (parallel) Andrew's.
What did I do wrong?

Don't forget that each individual bearing will be rotating somewhere around 6 to 12 times for each rotation of the tire (it varies quite a bit with each bearing design) ... that kicks her up to around 26,000 RPM ... more believable that it could fail now.

[KCStudly]

Hmm... My number doesn't match (parallel) Andrew's.
What did I do wrong?

Circumference = Pi x d not Pi x r.


I have seen some rather large Timken taper roller bearings that were only rated for about 300 rpm due to the load that they are designed to carry. These were something like 5 inch id and supported a very large cantilevered load; in mixer transmission.

[john]

Hmm... My number doesn't match (parallel) Andrew's.
What did I do wrong?

Circumference = Pi x d not Pi x r.

That's it! Crossed it up with area.

3.1416(16") = 50.2" or approx 4' per revolution.

5280'/4= 1320 revolutions per mile.

Or 79,200 revolutions per hour at 60mph
Converting that from hours to minutes would give 1320rpm at 60mph.

Or 132,000 revolutions per hour at 100mph
And converting that from hours to minutes would give 2200rpm at 100mph.

Much closer to Andrews numbers...

Knew it was my mistake.

[angib]

I was using 17.4" diameter from Carlisle's trailer tyre catalogue. But then I converted it to 440mm because I can't work in these heathen inch and foot units any more, even if I did use them at school.

I have a friend who has towed his 8" wheel boat trailer at 100mph when it was that or miss the first race. OK, the trailer is only carrying 100-200 lb dinghy but those little tyres didn't blow up or cause the end of the world, like folks will tell you.....

[legojenn]

I have two trailers with 8" wheels. One is my Motomate camper, and the other is a Harbor Freight 40x48" utility trailer. I replaced the HF bearings with Timken ones on the utility trailer. I have run both trailers well over 120km/h which is I think close to 70 MPH without any harmful effects. I've had no failures to the present day.