Topic: 17" rear Comstar rim, which size tire would be best - 120/90-17 or 130/90-17?

[Yamahawk]

Ok, my tire selection is narrowed down, and I am going to replace the rear tire next. I am having a 100/90-19 installed on the front, and now I would like the rear replaced, and currently have a 130/90-17 Dunlop D404 on there right now. I understand that my rear rim may better suit a 120/90-17, so I have a choice of the two sizes, 130/90-17 or a 120/90-17.
 I am thinking the 120 series, due to the rear rim being a ComStar 2.50-17, I believe. The widest on that rim size is 130, so which would handle better?
Charlie

[seanbarney41]

Thinking you actually have a 2.15x 17...if so get the 120.  I have 130 on a 2.15 and you can not use all the tread so it's squareing off fast and makes the bike feel kinda heavy and bloated

[Yamahawk]

Thinking you actually have a 2.15x 17...if so get the 120.  I have 130 on a 2.15 and you can not use all the tread so it's squareing off fast and makes the bike feel kinda heavy and bloated

Yeah, not sure what the ComStar is, as it has no rim markings like normal rims have. So, I googled it, and came up with iffy info on rim width. Someone from this forum 'thought' it was 2.50" width, and it kinda looks like a wider rim than the steel ones, but not exactly sure. I know the tire on there now is a 130/90-17, but it looks rounded like it's a little large for the rim, that's why I was thinking it would be a sweeter handling with the 120/90-17.
Anyone know for sure, as I think this came off of a drum brake 1978 CB750A model, along with the front wheel, and possibly the forks also, as they say 75 in the bottom of the fork leg....
Anyone...? Bueher..Buehler...?
Charlie

[Flyin900]

Charlie if it is the CB750A Comstar rim the tire in imperial size shows as 4.5 inch and converts to a 120 width on the tire charts. I would stick with the Honda spec size for best stock performance.

[Yamahawk]

Yeah, a 120/90-17 would be a good handling tire I believe, and if Sean is right, and its a 2.15 rim, would be appropriate. I'm thinking, either way, it would out-handle the 130/90-17... PLUS, it's CHEAPER lol... win-win, I say!
Charlie

[Yamahawk]

I was at my friend John's shop Motorcycle Solutions yesterday, picking up my front rim, newly shod with a Shinko 712 in 100/90-19, and saw one of the Shinko 705's in 130/90-17 on a an adventure bike. The tread blocks looked larger and the gaps wider on that tire than the pictures online. So, I am going to try the 120/90-17 rear. It will fit either the 2.15 or 2.50 width rim I have, and give a nice, light profile either way. I am thinking if the 705 was rounded or 'pinched' on the rim it would exaggerate the block gap by spreading them out a little too. The 120 won't be pinched on either of those rim widths, Plus, the 120 should be a lighter tire, and unsprung weight is always good to have less of. We'll see how it handles, and hey.. it will wear out eventually, and if I don't like the way it handles, I can replace it later in the season.
Charlie

[Erny]

Charlie, I had the same dilema (see my other thread).
As on my K7 issue is with rear one, the same as yours, 17"... Rim is the same as yours, 2.50".
Searching on net, consulting etc. Finally decided to go for 120/90 17.
And from very limited offer on the market, I choose Bridgestone BT45.

Hope bike will handle well

[Yamahawk]

I am sure that the BT45 will be a good handling tire, they have been very good for cornering, maybe not so much for longevity though. But our bikes aren't high horsepower either, so are easier on them.
I think the 120/90-17 will be the better handling tire.
Charlie

[seanbarney41]

maybe not high power, but high weight eats tires fast

[Erny]

I don't expect many miles a year. Max 1500 a year. Like that aging of tires vs mileage brings me to replacement at the same time I suppose...

[MikeSimon]

Yeah, not sure what the ComStar is, as it has no rim markings like normal rims have. So, I googled it, and came up with iffy info on rim width. 

Strange thing, that. All the Comstars that I have, do have a size marking on them. What is the 17" Comstar originally from?

[Yamahawk]

Yeah, not sure what the ComStar is, as it has no rim markings like normal rims have. So, I googled it, and came up with iffy info on rim width. 

Strange thing, that. All the Comstars that I have, do have a size marking on them. What is the 17" Comstar originally from?

Mike, i actually found the front size, its a 1.85 - 19 and its marked on the center ridge. I will have to look at the rear again to see if i can spot it.
Charlie

[MikeSimon]

Mmmh. The Comstars were usually marked on the rim. All of mine, CX500 turbo, CBX1000, CB1100R are like this:

[Yamahawk]

Ok! I found the rear rim size, it is a MT2.50-17 rim. So, today I visited my friend Mike Bores out in Huron Ohio, and was picking up a couple rims for a friends 87 CBR600 Hurricane, and found a 130/80-17 Shinko 705 almost brand new, for $25... That will be the new rear tire... still had the tits on the tread, and maybe had a couple hundred miles on it.
The Hurricane rims were chrome, and the front needs wheel bearings, and hope that's it. The rear has the rubbers, drive sprocket and carrier, and a disc in good shape. Also had two tires on them in pretty good shape, a Dunlop ArrowMax 140/80-17 rear I believe... and a 120/60-17 ContiForce front tire. Both with decent tread. My friend should be pretty happy if the front doesn't wobble when we change the bearings out!
Charlie

[Yamahawk]

Well, after getting the tape and label that they put on the tire, I noticed some damage on the bead of the tire... what do you think, should I try to run it tubeless, put a tube in it, or just exchange it for a Bridgstone I saw there?
Charlie