Question about wheel /tire size on 1975 Boler

[Beverly Jones]

I heard the larger the wheel, the fewer revolutions so wheel bearings last longer.
What would you suggest is the largest size wheel to install on a 75 Boler?

Thx,
Bev

[RogerDat]

Fewer revolutions at a given speed. Slowing down a bit will let tires and bearings both run cooler. That said....

If you have a 4 bolt hub I think your pretty much stuck with 13 inch rims. Tires will be about 24 inches tall, I may have seen some that were a little taller but not much.

A 5 bolt hub is pretty much required to get 14 or 15 inch tires. If purchasing an axle I think the 5 bolt hub has a larger spindle and takes an 1 1/16 inch bearing which is larger than the 4 bolt spindle 1 inch bearing.

Some of those that have done axle replacement on bolers can tell you what is possible given the wheel well size, and what axle down angle is required for larger tires to clear the top of the wheel well.

Properly maintained with grease, and replaced when showing signs of wear bearings should not be failing from heat at normal trailer speeds. They are not expensive, hard to replace, or even costly to have a shop replace. I guess I'm saying if I was buying an axle and knew I was going to do lots of long distance highway cruising I might consider the cost of larger rims to get taller tires, otherwise I would not worry about it. Put a spare set in the tool kit "just in case" and call it good.

[Roy in TO]

Originally Posted by Beverly Jones

What would you suggest is the largest size wheel to install on a 75 Boler?

That depends on many things. 1st question I would consider is how is your torsion axle? If it is still flexible enough to move as intended while travelling you could measure from center of the spindle to the top of the wheel well and subtract 3", that will give you the maximim radius. But then you have to be cautious to make sure the tire fits between the body and hub while installing or removing.

I encountered that problem on the first tire swap and had to temporarily drop the axle.
http://www.fiberglassrv.com/forums/f...tml#post133630

[Bob Miller]

Properly maintained wheel bearing will last 100,000+ miles and it costs all of about $100 for new ones. Changing wheel and tire size just to reduce bearing wear is false economy.

FWIW: When I buy a used trailer I start out with a new set of bearings, races and seals, then I know how long the existing bearing set is going to last.

BTW: DO NOT use the Armstrong (hammer) method of seating new races, have them pressed in with a hydraulic press.

[Brian B-P]

While it is true that a larger overall tire diameter will reduce the rotational speed (for the same road speed), it will also increase the leverage of the tire when under later load (when being pushed from the side such as when turning) which is harder on the bearings.

I wouldn't worry about adequately maintained bearings surviving at highway speeds for the entire multi-decade life of the trailer. Trailers get towed much less per year than cars get driven, and similar bearings in cars last for the life of the car. I think trailer bearings are killed by their owners, rather than die from overwork spinning too fast or too long.

If the axle were replaced with the size that normally used 5-bolt hubs (3500 pound axle capacity), those hubs would use larger bearings which would have more life even without a change in tires. I wouldn't consider doing that expensive change (which would also increase weight) just for more bearing life.

Originally Posted by RogerDat

A 5 bolt hub is pretty much required to get 14 or 15 inch tires. If purchasing an axle I think the 5 bolt hub has a larger spindle and takes an 1 1/16 inch bearing which is larger than the 4 bolt spindle 1 inch bearing.

5-bolt hubs are available for the same axle, fitting on the same bearings. The Dexter application catalog lists both 4-bolt (4 on 4.00 bolt circle) and 5-bolt hubs (5 on 4.50 bolt circle). The page of hub parts is headed "440 AND 545 HUB GROUP" (the "440" means 4 bolts on 4" circle and the "545" means 5 bolts on 4.5" circle), and the illustration happens to show the 5-bolt hubs.

I wouldn't change axles to get 5-bolt hubs, but maybe if I were buying new brakes and hubs/drums anyway I would make the change... if those hubs are readily available. Of course, that would require a wheel change, even if staying with the same tire size.

By the way, Dexter currently uses L44649(cone)/L44610(cup) for both inner and outer bearings on the Torflex #9 (up to 2200 pound capacity) axle (and even the size smaller than that); they describe the spindle these go on as 1 1/16" (not 1"). This same size is used as the outer bearing on the 3500 pound axles, but the 3500 pound have a larger inner bearing. I think 1" bearings were previously used by Dexter, but now are found only on some other (typically cheaper) brands.

[Brian B-P]

Originally Posted by Bob Miller

BTW: DO NOT use the Armstrong (hammer) method of seating new races, have them pressed in with a hydraulic press.

Sure, if you have one, but Dexter says in their manual to use a brass drift punch to place the new bearing cups, ensuring that they are evenly seated. One trick is to use a large socket as a drift (no, it's not brass...) to push it in evenly.

Bearing presses also don't have to be hydraulic (a rack and pinion press works fine), but I get the idea: a press pushes the bearing race (cup) in straight and square, rather than being cocked to one side by hammering it on one point of the periphery at a time. I don't actually know anyone with a rack and pinion press, but I've used them in shops long ago (back in school) and they still work... and this one is only $65: Northern Industrial Arbor Shop Press — 1-Ton (I have no idea if it is any good). Too bad it doesn' have enough throat depth for hubs with brake drums. Wildly guessing, one ton seems like enough, but bigger units are available.