Topic: Rear Wheel / Tire for 1977 CB750K, Rim Size?????

[scotty77]

Hi everyone,  I've searched the forum and the internets to its extent on the subject and haven't been able to get full confirmation on this. I'm trying to replace the rear tire on my '77 and originally ordered an 18" which I found out was incorrect the hard way. At least I got a refund.

Now I know the stock was a 4.50-17. However, I do not know the rim size and the wheels are at the shop! I read that a 4.50 is closest to a 120 so After reading some recommendations on here I ordered an Avon RoadRider 120/90 -17.

However now I am seriously doubting the size as I saw on Avon's website the recommended rear tire for the '77 CB750 is the 130/90 - 17. The recommended rim size for the 120 are rims 2.50-3.00 and the 130 is 2.50-3.50. Then the tech at the shop tells me its a 4" rim! I'm totally at a loss now.

Help me out, someone, as I need to get off this tire rollercoaster!

[Don R]

It's not a 4" wide rim, I didn't find the width but the rim number is 42701-425-771.  I just put a 17" 120 on a kz1000 it looks fine and works great. 

[Bankerdanny]

The rim size should be engraved on the rim near the center by the valve stem.

[scottly]

I've got a K7 rear rim I can check tomorrow if someone doesn't confirm the size first. Like Don said, I do not recall it being 4" as the "tech" told you..

[seanbarney41]

it is most definitely not 4" wide rim lol

[Tracksnblades1]

I have a 76 750F1 that the previous owner had installed a 4x16inch rear rim with a 5.10 H x16 tire mounted on it. That rim they referred to as a hog wheel, but it had 40 spokes instead of hogs 38. The next replacement tires were Continental SuperTwin and later to a Metzler on that rim,  both 130/90 x 16. Each company at the time recommending the 4 inch rim width. The old Metzler just barely missed rubbing on stock chain guard. I know it's apples to oranges. I think the  17 / 18 will be a better combination.
👍

Amazon has Dunlop 404  130/90 x 17 with rim requirement of 3 inches...

[754]

The 17 is 3.00 wide I think.
 On those years they marked it on the side of the rims something I never really liked.
 But I like the fact that the Honda 17 rear sort of matches the front rim.... I mean a lot better than a Hog 16 inch rim.

[scotty77]

The rim size should be engraved on the rim near the center by the valve stem.

I don't have the rim here, which is part of the problem, but I will call again tomorrow to see if they can find it.

[Stev-o]

When I had a K7, I put a 130/90-17 Dunlop on the rear.  A 120mm will work but is .39" narrower than the 130.   I'd put a 130 on it.

[Erny]

Scottly77,
I had similar question year ago, when I freshly purchased K7 see here https://r.tapatalk.com/shareLink?url=http%3A%2F%2Fforums%2Esohc4%2Enet%2Findex%2Ephp%3Ftopic%3D170533%2E0&share_tid=170533&share_fid=13548&share_type=t

On my K7 I have on rear rim stamp 2.50x17.

I put rear tire Battlax 120/17. However found out that it is only 115mm wide. Made me crazy, I should have put 130..
On the other hand side, bike is very nimble in curves.
But here in Slovakia, you never know if technician at checks will not refuse it as not compliant with original specs..

[754]

I am going to put this out there..
 Many of us will think it looks better with 130.. myself included..
 However it will likely handle better, and roll easier, with a 120..

[Old Moe Toe]

The rim size should be engraved on the rim near the center by the valve stem.

I don't have the rim here, which is part of the problem, but I will call again tomorrow to see if they can find it.

I have got a 17 rim here and just checked it. Bankerdanny is right it is stamped near valve hole.
2.50 x 17.
Noticed a luckless lizzard had got itself caught in a spokehole too.
I have a 17 inch fitted on the back of my K2 paddock basher and much prefer it over the original back rim. Tyre size is 130/17. The overall maximum diameter of the 17 inch tyre is so close to the dia of the standard tyre there is not a bees dick in it.

[Sething]

I have a 1977 CB750K and bought Avon Roadriders. I went with 120/80-17 and they look fantastic. However, based on the comments from the old timers, it sounds like you may like the 130 better if you’re going for looks.



Honda 1977 CB750K

[scotty77]

Hi All!

Thanks so much for the replies!

What a sad end for that lizard!

I gave the guy at the shop very clear directions, thanks to your advice, and he did find the stamp and it is 2.50x17. I know a few of you recommended the 130/90-17 but I think I'll stick to the 120/90-17 I already ordered so as not to pay a restocking fee and I kind of like the skinnier look for the build I am going for. If not I'll order a 130 next time.

Thanks again for the help!

-scotty

[Sething]

Here are some pics for you. I actually found one that I measured and took a pic.
3.64 inches from outside edge to edge.
Hope it’s helpful.

[Bankerdanny]

The outside measurement is not important, it is the measurement from inner bead to inner bead that matters.

[Sething]

Honda 1977 CB750K