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Boat Trailer Wheels

Posted: Mon Jun 19, 2017 9:33 am
by Jefecinco
I recently learned that boat trailer wheels as well as most aftermarket automotive wheels are lug centric. OEM automotive wheels are hub centric. Trailer and aftermarket wheels are lug centric so they can fit any hub. OEM wheels are made to fit specific models and are close fits to hubs.

This matters because the balancing of trailer wheels must be done differently to achieve acceptable balance tolerances. Most often this is done by using a balancer adapter to ensure the wheel is centered on the balancer in the same way it would be centered on the trailer hub.

Not every tire shop has the required adapter.

I lack expertise in wheel and tire maintenance. I would welcome comments from anyone with knowledge on the subject.

Re: Boat Trailer Wheels

Posted: Mon Jun 19, 2017 11:13 am
by jimh
JEFE--thanks for bringing this topic to discussion. First, I was not aware of the difference in wheels. I searched for some information about the meaning of HUB-CENTRIC versus LUG-CENTRIC. I found several good resources that explained the difference. Here is a good resource with illustrations:

In wheels that are made as HUB-CENTRIC the wheel fits snugly against the hub which provides support along with the hub's lugs. There is no gap between the hub and the wheel. Wheels of this type are used by automobile OEM's because the support and centering of the wheel on the hub is better; the wheel resists impact loads encountered on typical roads. Also, the exact center of the wheel is the center of the hub.

In wheels that are made as LUG-CENTRIC the wheel does not fit snugly against the hub; there is a gap between wheel and hub. Wheels like this are made for aftermarket applications because they will fit on a wider variety of hubs. The drawback to the lug-centric wheel is the reduced support from the lack of firm fit to the hub. The lug bolts carry all the loading. Lug-centric wheels are often used on low-speed vehicles like golf carts. Also, the exact center of the wheel is the center of the bolt-circle of the lug holes, and may not be precisely coincident the center of the hub.

I have heard a old wive's tale: do not get trailer tires balanced. I never heard any reason behind this. I can understand this old rule better now. I presume that most tire stores would balance a wheel with the expectation that the wheel is a hub-centric design. The wheel is usually fitted to the balancer with a temporary mount that does not use the lug bolt holes as a means of fastening the wheel. If a lug-centric wheel is balanced by using the hub of that wheel as the precise center, there could be a difference in the location of the actual center of the lug-hole bolt-circle and the hub hole. This could result in an improper balance.

Also interesting to note: this difference reveals the use of lug-bolts instead of lug-nuts on many trailer wheels. On my E-Z-LOADER trailer, the hubs do not have studs; the hubs have threaded holes. The wheel is fastened by five lug-bolts, and the bolts have a tapered shaft. The tapered shafts of the lug-bolts helps to center the lug-holes in the wheel over bolt-holes on the hub. Also, a lug-nut usually has a tapered face on one side to help accomplish the same centering on the hub studs.

Re: Boat Trailer Wheels

Posted: Mon Jun 19, 2017 1:43 pm
by Jefecinco
Several years ago we had the same trailer brand with 16" wheels and tandem axles. It also lacked studs and used lug bolts.

Re: Boat Trailer Wheels

Posted: Mon Jun 19, 2017 7:32 pm
by Jefecinco
I'm told that Costco has the requisite lug centric wheel balancer adapters.

Re: Boat Trailer Wheels

Posted: Mon Jun 19, 2017 9:32 pm
by number9
Don't believe this should be a significant concern for most members when having their trailer tires balanced. As long as the balancer uses a properly sized centering device there is no real advantage to a lug-centric adapter.

Have never been a tire tech per se but did work in gas stations in a past life, bubble and spin balancing tire/wheels for customers and myself. The willingness of the balancer to take the time to get it zeroed rather than just within tolerance and ensuring the machine is calibrated is more important than a adapter in most cases.

From Hunter accessory PDF.
Hub-centric and lug-centric wheels all use the hub bore as the center locating position of the wheel. The hub bore centerline is virtually the same as the lug holes.


Re: Boat Trailer Wheels

Posted: Tue Jun 20, 2017 9:18 am
by Jefecinco
In the sentence you quoted the qualifier "virtually" is used. Another word for virtually is "almost" with virtually inclining toward certainty. It takes very little error to make a tire unbalanced. I would prefer to have my trailer tires balanced with a lug centric adapter on the balancer. Obviously if it is not available I'll settle for a properly sized centering device.

Most of us do not put enough miles on our trailers to worry about the cupping caused by out of balance tires necessitating early replacement. My goal is to balance the tires to minimize vibration when towing because I believe vibration causes wear.

Re: Boat Trailer Wheels

Posted: Tue Jun 20, 2017 2:36 pm
by porthole
There are differences in lug nuts as well

Conical or spherical for instance.