Wide Tire Kits
The parts used for final belt drives on Shovelheads do lend themselves very good for the installation of wider rear tires, either with a (narrower) belt, or with a chain. The final belt drive inner primaries and wider swingarms provide the extra clearance needed for wider tire applications, without having to offset the transmission, primary case, and motor sprocket. The rear tire in the image above is about 150 mm wide (as opposed to the stock 130 mm tire width). The bike is equipped with a slightly narrower belt of 1-1/8" (28.6 mm) as opposed to the stock 1-1/2" (38.1 mm).
Mullie Motors can provide you with the necessary parts to enable you to install wider tires on your shovel. Starting with the 150 shown in the image above, and ranging up to a 180 mm without off-setting the tranny and primary drive!. Here are some of the options:
- Narrow belt and standard (belt-drive) swingarm: As shown in the image above, a tire of up to 150 in width can be used in the stock frame and FX fender by using a slightly narrower belt (1-1/8" in stead of 1-1/2"). In this application, the tire clears the belt by about 3/8" (about 9 mm). So here even a 160 mm tire could be used provided that the fender, struts, bolts, and frame can provide it. Also, depending on how far the wheel is mounted to the front in the swing-arm slots, the front (tapered) portion of the swingarm can be an issue.
- Narrow belt and extended (belt-drive) swingarm: Some HD models are equipped from the factory with 20 mm "extra-strong", kevlar belts. These belts come in only a few lengths, but as can be seen here, the 132 teeth belt is an appropriate fit with a 2" extended swingarm. Compared to the 1-1/8" (28.6 mm) belt, the 20 mm belt would provide 8 mm more clearance on one side. Hence, this would allow a tire of up to 180 mm to be fitted. In addition, the extended swingarm provides more clearance for the tire to the frame (as it is moved further back). Mullie Motors stocks 2" extended swingarms and 132 tooth, 20 mm belts.
- Chain and standard or extended (belt-drive) swingarm: If you prefer a chain over a belt, that is of course also possible. A standard 530 O-ring chain can be about 1" (25) mm wide. The belt-drive inner primaries have about 0.7" (18 mm) more clearance than the chain drive primaries. So, an off-set sprocket can be used. Therefore at least a 160 wide tire can be mounted using a stock or extended (belt-drive) swingarm, but also 170 or even 180 mm tires could be squeezed in there. Mullie Motors offers aftermarket sprockets with several off-sets, or we can machine you one with a custom specified offset.
Please contact us through firstname.lastname@example.org to order your wide tire parts or for further inquiries.
Here are some tips and hints about installing wider rear tires on late shovels:
- A 150 tire is about the widest you can fit inside a stock HD FX rear fender, the fender struts, and the fender mount tabs on the frame. Anything wider and you will have to go to a different fender and either modify your fender frame tabs or go to an extended swingarm to clear the tabs. Also note that it might be necessary to alter chain or belt guards, brake anchors, etc.
- Always make sure to check that you have sufficient clearance for a particular tire once mounted. Not only along the sidewalls, but also inside the fender and along the circumference of the tire.
- Always make sure that the wheel, sprockets, pulleys, chain and/or belt are properly alligned. Misallignment can cause premature wear and even breakage of these drive components.
- If you want to run a narrower belt your rear pulley needs to be narrowed. Mullie Motors can provide this service for you, see here .
- Be aware that narrower belts are often less strong than wider belts. Some manufacturers sell their narrow belts with the disclaimer "only for custom and show applications". Nevertheless, HD sells stock bikes with belt as narrow as 20 mm.
- Be aware that the tire designations of different tire manufacturers indicating the width of a tire are merely indicative. For instance, the tire in the image on top of this page is officially designated as a 140, even though the actual width of the tire once mounted is a little over 150 mm(!). Always make sure what the final tire width will be when mounted on your rim to avoid unpleasant surprises.
- Be also aware of the fact that not all tires can be mounted on all rims. Wider tires may require different rim widths than your stock HD rim width. Always follow the tire manufacturer's advice on permissable rim width for a particular tire.