The Tale of the Tires..

[crazy steve]

With all this discussion about FD swaps, highway RPM and such, I thought I would show just how much tire sizes have changed since these bikes were new...

[IMG][/IMG]

Left to right, you have: a 4.50H-17, a new 160/80-16 (more on that later), a 130/90-17, and a 130/90-16. Now, the 4.50 has about 60% tread left (but is over 25 years old!), and the two 130s are pretty much worn out. But even if the latter two were new, that would increase their diameter by only about 1/2". As shown, there's nearly 1" difference between the 4.50 and the 130/90-17, and almost 2" between the 4.50 and the 16" tire. That's a lot in terms of circumference, and explains why the Specials respond so well the the FD swap.

The 160/80-16? As you can see, this is pretty close to the same size as the OEM 'standard' tire (about 3/8" smaller if the 4.50 was new), so that's my choice for a rear on one of mine. But this needs fairly extensive mods to the swingarm to make it fit due to it's greater width (6.15") so it's not an easy install.

[jetmechmarty]

That's interesting. Thanx for that effort.

[natemoen]

What all do you think you will need to do to the swimgarm to get it to fit?

[crazy steve]

Already done it...

I had to cut the 'tire notch' deeper (beyond the driveshaft), then refill the cut-out while allowing maximum clearance. I also had to remove the stock anchor pin for the rear brake and make it removable. When I actually fit this to the bike (it's still all over the shop), I'll post a 'how-to'...

[natemoen]

I would very much so like to see what all goes into getting that tire on.

[yamahansolo]

Very interesting... also you wouldn't happen to be able to rinse the mud off would you so we can see your chicken strips
And I would love to see a new 130/90 17 next to the 4.5h. I wonder how thick the tires are at the center if cut open. Maybe the older tires had much thicker rubber so the last longer...? Any estimates on how deep the rubber on the 4.5 is. I have a couple of diner carcases that are the 130/90 17s. I could cut one open and see. Maybe the tire manufacturers are gipping us big-time .

[yamahansolo]

I saw a 491 dunlop on t99 fords bike in my 2011 calender he has the cafe racer right after my bike. It looks alot taller than the tire on mine. I think I was running the continue tour or milestone?

[crazy steve]

... Maybe the older tires had much thicker rubber so they last longer...?

LOL! Not hardly.... that particular tire had maybe 3K miles on it, and was the third rear tire inside of 15K that I had put on. The OEM Bridgestone only went about 5K, I think I tried a Avon for the second and it wasn't much better. The one in the pic is a Continental, and might have gone 8K if I hadn't wrecked the bike.

I did compare the new 130/90-17 I mounted on the SG (standard rear wheel) to that 450H and it still wasn't as tall. I will say that the newer tires generally seem to 'track' better, but they haven't increased wear one bit that I can see...

[motoman]

The one in the pic is a Continental, and might have gone 8K if I hadn't wrecked the bike.

I'd still be runnin' the K112 and RB2 on my Venturer if they they were still done in the 17". The Conti' rear WAS a bit softer compound and IIRC got anywhere from 6-10k depending on load and riding style. Interesting you still have one around Steve. The bike road and handled the best with these tires and stuck like glue hard cornering in the rain..........yup, the old 450/17 dropped it bout 200rpm less at any given speed than the shorter metric sizes of today.