Start with your frame rail width. That will determine your widest available possibility without cutting the rails.

Assuming your going to keep the frame rails as is, start measuring out form the imaginary wheel centerline and see what you have and what you will need for clearance.

I have run the late model 00 Twin Cam swing arms (up to where they went wider yet) on the Evo frames. Use the TC belt and pulley to gain belt to tire clearance. The newer belts are even narrower the the 1 1/8" 00 stuff. Still your frame rails will limit you.

We were installing 180's on stock framed 00's with a fender change and correct wheel/sprocket spacing.

If your willing to cut the frame horns off that will open up the width possibilities.

 

There you go first hand knowledge.

 

I'm running a 160 inside a 94 Heritage fender, so I believe that assertion is incorrect.

 

Puzzled was the late model swing arm pivot bolt the same as the Evo's? Never had one around when doing things. Point here is gents a lot of Harley parts will interchange just like they did in the old days. Asking the clowns at the parts counter or service dept at your dealer will very rarely get you any good info. They are stuck on pushing their stuff in parts and and many MMI grads changing parts these days didn't know jack about Harleys before they went there.sites like this and club chopper and such hold a wealth of info.

 

Not all brands of tires are exactly the same, but 160mm is 6.29"...the inside of an unmodified softail fender is 6.75 not counting the mounting bolts or wiring tabs...not much room for error seeing few Harley fenders are exactly centered. So I will stick by saying 150 is the biggest tire you can safely put on an unmodified softail... hell you usually have to turn the fender mounting bolts around to put a 150 on there... after you cut a brand new tire from it scraping the fender, you will agree

 

That's strange because I'm running a 150 on my 07 Heritage and there's about 3/8" space on either side. Considering there's bolts and wires in there, a 160 would be tight (and the 07 and up has the same swingarm as a fatboy), but narrower fender and fender struts. Earlier models were narrower still.

I guess if you can go 160, I can go 180.

 

Comparing an 07 to a 99.

The Evo bikes are narrower. The frames went even wider with the 200 series tire (whatever year that was).

 

That is true with the brand of tire. Same goes for the profile of the tire also (although not as common in MC tires).

When we first starting putting 180's on the early Twin Cam frames we would either use a thin nylock nut on the inside (similar to a jam nut) or install the bolt from inside the frame rails out. Later on we started drilling and tapping the frame rails and used them as the nut. The early Twin Cams mounted the fender between the frame rails as opposed to over them. We searched for a fender that would install over the rails. All of this to give us as much clearance as possible between the rails.

 

That's a good question. I'd have to look at my books and see if the bearings and bolt are the same. We know they are the same width. I'll look if I remember when I head out to the garage.

A lot of stuff crosses over. I wonder if a Rocker swing arm will go on a late model Softail.....

 

I have a 160 Avon. It's as wide or wider than most 160 tires. It is close but it doesn't rub. I had to address an issue with one fender bolt, but it was no big deal.

The point is, you said that you can't go bigger than 150 "without cutting the frame horns and installing a wider fender". That is just not true, a lot of people are running 160 tires without cutting the horns or changing to a wider fender. After I called you on it, you back peddled, and now your story is that it's not safe? I don't agree. I wouldn't have anything on my bike that is not safe.

It's better to stick to posting things you know for sure to be actual facts. Spreading misinformation isn't helpful to anyone; it only serves to propagate ignorance.

Earlier models are narrower than what? The 94 Heritage fender that I have is the exact same width as an 04 fender (7"). So what years are you saying are wider than 7" (besides the 200 rear fenders)?

Yes it is tight, but like I said, it fits and doesn't rub. Are you serious about fitting a 180 inside your fender, or were you just being sarcastic?