In the Bikernet Garage, we show you how to install Harley-Davidson's 150-16 wide-tire kit. Well, for those of you out there looking for something different, there is another option that gives you 150 rubber with a different look.
I'm talking about swapping out the stock 16-inch factory wheel and upgrading to the popular 18-inch Akront spoker with Avon 150-18 low-profile rubber. Why consider this? Well, there are several reasons that make this an attractive choice. First of all, stock rear brake rotors and belt pullies are quite large in diameter. The rotor alone measures 11.625-inches, and depending on what pulley you have, you end up with 2 massive wheel covers that virtually obscure the beauty of a spoke wheel, or any other type except maybe a solid rim.
Sure, many of the current popular wheel manufacturers also offer rotors and pullies to match the designs of their billet wheels, but the idea in this series is to get to the big rubber. Customizing with fancy rims and accessories will come later, so for now, we'll continue our look at the 18-inch rim as an alternative.
To continue, the 18-inch wheel opens up the area under the rear fender which shows off a lot more of the wheel and works well visually with the large rotors and pulleys. They allow you to run the low-profile tires such as those we have been spotlighting from the Avon line, with their rounded tread patterns for extra cornering rubber and bad, bold looks. Even cleanup is easier on these larger rims, because with the added diameter, you can get your polishing cloth to the rim even with saddlebags in place.
Slipping a 150-18 up under the rear fender of a stock bike is pretty damn easy, and it requires no major surgery such as removing the primary to change belts as in the H-D kit. In fact, all you'll need for this conversion is the rim, tire, tube, strip, pulley spacer and enough tools to slip the rear wheel off. You'll also need the assistance of a machinist, but the work there is minimal. Let's get into it.
First off, let's have a look at some measurements. The bike I used for this conversion was a 1990 FXSTS Springer Softail with a stock chassis. The only difference worth mentioning was that it had a Metzeler 140/90B16 rear tire on it as opposed to the stock 130. The wider 140 measured out at 5.570-inches wide on the stock 16 x 3.5-inch rim. The Avon 150/70VB18 measured 5.930-inches wide mounted on an Akront 18 x 4.25-inch rim. Diameters for the two meats panned out at 25.625-inches for the 140-16 and 26-inches even for the 150-18. So what we ended up with was an increase of .360-inch in width and .375-inch in diameter. Remember that measured to a 130, the difference in width is considerably more, almost an inch. And even with the 150-18's larger size, no fender clearancing was necessary to make this sucker fit. It's pretty much a bolt-in job.
Photo 1
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Photo 2
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So here's where we start: A brand new Avon 150 mounted to a chrome Akront wheel assembly from Custom Chrome (photo 1). Akront's were the choice among builders when the whole wide-tire craze hit us over 7 years ago, and they still offer classic spoke style and a wide variety of rim sizes to choose from. Custom Chrome has become the exclusive distributor for Akront wheel assemblies in polished and chrome finishes. In fact, all of the parts we used can be directly ordered from your CCI dealer, and I'll lay out a complete list at the end of this article.
Photo 3
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Photo 4
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Next, the rear pulley had to be spaced outward in order for the belt to clear the side of the wider tire. This .200-inch spacer from CCI (photo 2) did the job, although we used two of them to get the right amount of clearance for the drive belt (even with the two spacers installed the belt tracking, both forward and reverse, ended up better than it was originally). With the pulley installed, take a good look and see how much more rim you get to see compared to the 16-inch wheel. The pulley on this bike is a stock 70-tooth, and is the largest in diameter, so the 18-inch rim really adds some well-deserved space (photo 3). In case you're wondering what that do-dad is in the center of the pullry, it's a Rivera 3rd bearing which provides additional axle support to the drive side of the wheel. It was already on this scooter prior to the swap, so I thought I'd mention it.
Now comes the part where the machinist comes in to play. Before I dove into this project, I spent the previous night taking measurements on the stock bike I was using. As it happens, this wheel/tire combo can bolt right in with no problem, except for the fact that the belt is shifted outward about 3/16 of an inch. Some folks would say that's good enough to run, but I was interested in finishing the job right. So what happened was this. The wheel needed to be shifted over to the right of the chassis about .225-inch in order to straighten up the belt and to give a bit of tire clearance. The way this was handled was to remove this amount off of the caliper bracket (photo 4) where the axle slips through it. But, instead of talking all of this cut off of one side of the bracket, I cut it off both sides to make the machining process a lot simpler. See, if the .225-inch was cut all from the outside of the bracket, some of the bracket itself would also have to have been milled away to clear the swing arm. In this case, I machined .100-inch from the inside of the bracket and .125-inch from the outside. This moves the rotor closer to the bracket, but not enough to hit, and since the rear caliper is a floater, it would ceneter itself.
Photo 5
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Photo 6
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Okay. Well, if we trimmed off .225-inch from the caliper bracket, then that much space had to be made up on the left side. Using an old axle spacer, I had it trimmed down to .905-inch, which was .225-inch more than the one that was on the bike before (photo 5). A trial fit of the modified caliper bracket showed me we needed some clearance between it and the locating brace on the swing-arm. We filed the brace (photo 6) and trimmed some off the caliper mount (photo 7) and were in business.
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Photo 7
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Slipping the new wheel and tire in place is made a lot easier with the upper belt guard removed (photo 8). Don't forget to place the caliper bracket on the swing-arm first, otherwise you'll end up fighting it trying to get the wheel on. Once the wheel was in place, the axle nut was torqued and the wheel was spun forward to verify we had clearance between it and the tire. Don't freak out if the belt creeps over toward the tire when you rotate the wheel backwards, that's a natural tendency for the belt when alignment isn't 100-percent perfect. As long as it tracks away from the wheel while rolling forward, you're OK
Photo 8
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Photo 9
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With everything looking good, the bike was set on the ground to re-verify clearances (photo 9) Even the rotor was free of any contact (photo 10) which meant all of the number crunching I did came out correct. Even the upper and lower belt guards went back into place with no trimming whatsoever. Now, the numbers I came up with for clearances and measurements were for this specific bike. We all know that even factory bikes will differ to some degree, so while you can certainly use my numbers for reference, don't assume they will be the same for every bike.
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Photo 10
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The final proof and satisfaction comes from checking things out with the bike on the ground. From the left side, straight on from the back or from the right (photos 11, 12, 13), the 5.930-inches of Avon rubber makes this Springer look super cool. More tread for cornering, fat, stylish looks and immense satisfaction that what should be a long, drawn out process is really quite simple. The biggest key to success here is taking the time to properly measure your clearances and spacing. Most people cringe when they hear "machine shop" but as you can see, the amount of machining is minimal, and now you're armed with the knowledge to tackle this yourself.
Photo 11
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Photo 12
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Photo 13
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Oh yeah, I did mention something about a parts list for this job, didn't I? Ok, here it is, complete with part numbers and from Custom Chrome (except for the tire, which you'll have to pick up from your local Avon dealer). I listed CCI replacement caliper brackets and axle spacers as an option so you can have the originals to change back to if you like. Also, depending on your own bike's measurements, CCI has axle spacers in a wide variety of widths that might eliminate having to have one cut up or made special. Of course we all know that most places don't charge suggested retail, so you'll probably get off cheaper than this. And, with the tools you keep in your garage, you can handle this swap like a pro.
PARTS LIST FOR 150-18 CONVERSION
Avon 150/70VB18 AM23 rear tire
08-120 Akront 18 x 4.25-inch Chrome wheel assembly w/chrome spokes (polished rims and stainless spokes are also available)
07-029 CCI inner tube
07-019 CCI rim strip
19-722 CCI rear pulley spacer
13-080 CCI rear caliper bracket (optional)
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