Hi all -
I have a 2005 Road King Classic. Here in Vegas, I've put three MT's on, after about 7k miles on each. After a Club mate from Canada kept suggesting the Darkside, I finally said I'd try it.

We measured the frame, the rear fender and felt that a 195/60R16 should fit.
I ordered the tire, inner tube (I have spokes), and got a local shop that has installed Darkside before to do it.
The entire time we took the old tire off and looking at the new one, he and I both thought the 195 was going to be too big for the rim, and also maybe too big for the fender. It was. Not only was it too big, but when I'd dumped the bike, the rear fender was bent (and likely the frame too - However, I'd never had any issues with the frame or riding the bike at any speeds. Always nice and stable).
But it was late, he wanted to take his kid home and I was 5 miles away. So after getting the 195 on the rim (not balanced), and installed, it looked like it would rub. And it did. The 5 miles home put a serious grove into the tire.
So I knew that needed to go.

Ordered a 175/60R16. Formoza 2D. Due to the excessive cost of having the last shop install the tire, my buddies and I installed the tire. We had a local shop de-bead the old tire (with the inner tube they didn't want to do much more than that). We got the 195 off, the 175 installed and took it down to get balanced. Due to the concern of the rear fender being slightly crooked, we had it replaced. There is no issues there. The tire doesn't rub, and it's all good.

We had a poker run that weekend, but my wife was riding with me. So the extra weight gave it some grip and as a Club we didn't go much faster than 75mph. I felt a bit of wiggling on the cement with groves part of the freeway, but I figured it was just the tire wearing in. For the past 2 weeks, I've only ridden the bike to work - which is 4.4 miles each way on surface streets. So I haven't felt too much concern.
Then today, I planned to go for a long ride - work that tire in a bit. Just myself. And WHAM.

I got on the freeway and immediately felt wobble. I could feel it around 60 and 65 mph, but the moment I reached 70 and was accelerating to 75, I could see the bike fishtailing all over the road as I looked down at the connection between the forks and the front frame. I've never seen that before. Never felt anything like it - well, that time that I was doing 117 mph downhill - was close, but this was a straight shot.

So I'm concerned. I had the tire inflated to 40 PSI and put it down to 35 PSI for my trip back home (I only went 5 miles as I didn't think it was safe, pulled over and let out the air). On the way home a buddy riding behind me said it looked like the whole bike was swimming.
I didn't have any of the these issues prior to going to the darkside. And after the cost of 2 car tire, a paid install, the down time and such - I'm nearly $500 into the Darkside, with a fed up wife. I'd rather not have to ask for another $250 to go back to the light.

What options or things need to be looked at? I'm trying to do the research, but I'm lost. I've seen things that say that it could be the shock bearings, swingarm bearings, or just tire pressure.

Thank you for your assistance. It's a beautiful 76'F outside, and I need to be on the road!

 

What I'm thinking could be the issue is the shocks. When we removed them to redo the fender, they leaked. I'd forgotten about it. So I got shock oil and a syringe thing to drain the oil and replace it. I'm hoping this is the cause of the wobble.

 

We put 10wt shock oil. 10oz per shock. I have the shocks at 30lbs each. Put the rear tire back at 40lbs. Wobble at 85-90 mph now. I'll take it easy tomorrow for a couple hundred miles, see if getting some wear on the tires helps. I could really use some ideas on this.

 

With the wheel mounted is there any play in the wheel bearings? I would put a used tire on just for a test to either confirm or deny the tire is the cause of the problem. Look at what you changed or removed and replaced first. It didn't do it before right?

 

Bent swingarm possibly? Alignment issue maybe?

 

Alright so after 250 miles yesterday in addition to the 150 I'd already put on, I'm still pretty worried about the wobble. I've found that the front tire is a bit worn, but should last me until the start of the summer. But since that could be part of the cause for the wobble, I'm gonna replace the front tire tomorrow morning. If that isn't it, I just won't be riding faster than 65mph. Which would be a shame, since I got those cams put in.
Yeah, the rear tire is the only thing that's different. The rear tire was balanced, but they didn't check the spokes. So I'll see if that's part of the equation.

 

Just a thought here, is anyone else running a CT on a spoke rim? For some reason I was thinking they only ride right on mag type tubeless rims.

 

I often have wondered that as well. But besides the inner tube aspect, I'm not sure what is different. But that's because I don't know.
I got the new front tire on, and that didn't make any difference.
So far, the darkside isn't working. I really want to figure this out however.

 

Yes, many of us were running CT's on spoke rims "years" before mag types were ever invented. And still do.

 

OK, so with the new Last of the Jedi trailer, being on the Darkside just isn't gonna work. I had to have a Dunlop 402 MU85B16 installed and just a few miles on the tire and I got zero wobble until about 90mph. And even that was the small typical wobble on two brand new tires.
I had done everything I could to keep that Darkside going. But it just didn't work out.
Oh well, now to deal with the Wife being upset and more cash into the bike.
Thanks guys.
Bishop