Fitting a 17" rear wheel to a R1100RS

[jagarra]

After the last discussion on the difficulty of finding the correct size rear tire for our R1100 I was on the lookout for a 17" wheel from a K1200RS or LT. One showed up on a bike from a wrecking yard about 120 miles from here so I went and purchased it. I also remembered that someone indicated that longer bolts were needed, so I also got the bolts along with the wheel. Today I pulled the stock set up and tried to fit the wheel, seems that the 170/60-17 tire on the rim won't clear getting into the cavity short of pulling the muffler or caliper, even with the air let out. But now for the bolt question, the stock bolts on my 1100 are 60mm long and the bolts for the LT are 54mm long, checking what protrudes it seems I have plenty of material to hit the hub on the FD, so am I missing something or is even a longer bolt required?
So far, I have calculated the size that ends up closes to stock is a 150/70-17, it's about 7 revolutions more than stock per mile.

 

[20774]

Since this is for an Oilhead, I'll move this to that forum. No need to repost...hang on!

 

[pglaves]

After the last discussion on the difficulty of finding the correct size rear tire for our R1100 I was on the lookout for a 17" wheel from a K1200RS or LT. One showed up on a bike from a wrecking yard about 120 miles from here so I went and purchased it. I also remembered that someone indicated that longer bolts were needed, so I also got the bolts along with the wheel. Today I pulled the stock set up and tried to fit the wheel, seems that the 170/60-17 tire on the rim won't clear getting into the cavity short of pulling the muffler or caliper, even with the air let out. But now for the bolt question, the stock bolts on my 1100 are 60mm long and the bolts for the LT are 54mm long, checking what protrudes it seems I have plenty of material to hit the hub on the FD, so am I missing something or is even a longer bolt required?
So far, I have calculated the size that ends up closes to stock is a 150/70-17, it's about 7 revolutions more than stock per mile.

I have fitted a 17" wheel from a 1998 K1200RS to an R1100RS. There is a 5mm difference in bolt length but I don't remember which way. So what you need to do is take off the stock wheel and bolts and then measure the thread exposure beyond the wheel when the bolt is inserted through the wheel. Then you need to find the correct bolt length that provides the same or very similar amount of thread exposure through the replacement wheel.

What worked for Voni's R1100RS was 170/60-17 tire instead of the 160/60-R18 tire. This is on an RS wheel, not an LT wheel. I don't know much about the LT wheel, or even if it will fit.

 

[jagarra]

I checked the part numbers for the wheels on the parts fiche, they were both the same.
I checked for a 160/70-17 first , but they were not many available now either.

 

[pglaves]

I checked the part numbers for the wheels on the parts fiche, they were both the same.
I checked for a 160/70-17 first , but they were not many available now either.

I always needed to take the bolt (capscrew) out of the rear muffler hanger and let the hanger swivel downward. Then I could grasp the muffler and pull it sideways a quarter to half inch which would allow the tire to slide right in. No need to remove the muffler; just move it a little sideways. You should try this.

 

[wynnd]

Why change?

I'm trying to understand the reason for going to a 17" wheel? It's about 1/4 inch shorter at the tire. Looking for better tire choices? Looking for a smidgen more power at the rear wheel? (Doubt one could tell the difference.) Better handling? (Doubt it would improve.) What is the reason? Just to be different?

 

[pglaves]

I'm trying to understand the reason for going to a 17" wheel? It's about 1/4 inch shorter at the tire. Looking for better tire choices? Looking for a smidgen more power at the rear wheel? (Doubt one could tell the difference.) Better handling? (Doubt it would improve.) What is the reason? Just to be different?

The reasons we did it were threefold. First, much better tire selections back then (2002). That is still true today. The 160/60-R18 is a bit of an oddball size. Second, much better availability. Few dealerships had the 160/60-R18 size in stock in any brand or model tire. We traveled on the bikes for 3 or 4 months each summer so a puncture that meant a new tire was needed could be several days waiting for a tire. Third, we were setting Voni's bike up for the 11 day long 2003 Iron Butt Rally where reasons 1 and 2 were critical.

Reasons one and two are still applicable today. They are important if you use the bike to travel as opposed to local riding primarily.

As an aside, there was/is an unexpected benefit on Voni's bike. There is a slight (few %) difference in tire circumference. On her bike this corrected both the speedometer and odometer to much closer to reality.

 

[jagarra]

Using a 17" wheels is a back up plan when I cannot find the tires I want in the 18" size. Even though my current PR3s still have enough life in them for this year, I am gathering information. When the thread started about the lack of PR3s out there I started checking availability of the correct tires for our 1100s. I was very surprised to see only a few brands that I would be willing to try, none of them Michelin. Running a PR4 is an option with a 17, so that opens up a few more sizes that are close to the stock circumference. As it stands right now the 1100 bolts look a little long, and now i have to pull the wheel again to measure the protrusion out the back. The K1200 bolts are 6mm shorter, I don't know if BMW has a length between those two. As far as ratios are concerned with using a 17" wheel, using a 160/70-17 gives you a ratio about 1% higher than stock, using a 150/70-17 gives about 1% lower than stock.

 

[52184]

When you remove the wheel use a depth gauge or butt end of a vernier caliper to measure the depth of the bolt hole in the hub. Personally, I’d use the longest bolts that fit without bottoming out, but bearing in mind the hole was likely not tapped with a bottoming tap so some headroom would be advised.

Best,
DeVern

 

[pglaves]

My approach was to make sure that the exposed thread through the wheel was equal to that from the original wheel/bolt OEM setup. DeVern proposes an equally valid approach, and I can offer a third.

Take a wheel bolt and screw it into the hub as far as it will go. Mark the remaining threads. Then measure the unmarked threads after removing the bolt. That is the maximum exposed thread for the bolts after inserting through the wheel. I would plan on at least one full thread less. I would also try this in all four hub holes just in case they are not all the same.

So, I decided to just look the parts up. The R1100RS 18 inch rear wheel uses a 12mm, 1.5 pitch bolt 60mm long.

The K1200LT and RS bike 5.00 x 17" wheels take a same sized bolt 55 mm long. The part number for the 55mm bolts is: 36 3 12 333 225

 

[jagarra]

Paul,

Thanks for the confirmation. Since the wheels between the K1200RS and LT are the same part#, it would figure that the bolts would be the same. After I changed the battery in my calipers the bolts that I got with the wheel measure 54.67MM so they will work.
Availability really showed up for a 17" tire, I googled for a Michelin PR4 in 150/70-17 and one popped up in stock available on Amazon. I am leaning on using the slightly smaller tire cause it lowers the bike 4MM, since I am vertically challenged, I need every MM I can get.

cheers

gg

 

[wynnd]

You sure aren't kidding.

I went looking at tires available in different sizes and the 17" rear wheel is the serious winner. I rarely change tires on a trip, but I do love taking trips and the last long one had a tire change in North Carolina for my PC800. On that bike I got 10-15K miles on a rear tire. I'm hoping to do as well on the RT, but don't know yet.