Author Topic: What's the widest tire I can stuff under my CB750 ??? (Read 16887 times)

ProTeal55 · « **on:** September 21, 2005, 01:52:35 PM »

Hey ,

Bored here at work , and was thinking about how I would go about stuffing a wider tire under the rear of my 1972 CB750K, to offset the front tire more. Once again , as with everything on this bike , handling is of no concern , this bike is all for looks....

Anyone running a wider rear tire on with the stock wheel & fender still in place ? I am going to bob the rear fender , or I might take it off completely, not sure.

The bike is a 1972 CB750K , and has been lowered 1'' in the rear thus far. The Bike has a 18'' wheel in the back now , and sports a 120/90/18 . Could i possibily run a 160 or a 180 ? I am sure I can stuff anything under their , just dont wanna deal with rubbing / bottoming out issues.

Any help is greatly appreciated......

ProTeal55 · « **Reply #1 on:** September 21, 2005, 01:58:48 PM »

2nd pic is of a 240 rear tire
3rd pic is a 300

kyre · « **Reply #2 on:** September 21, 2005, 02:00:46 PM »

which look sooooooooooo lame.

Geeto67 · « **Reply #3 on:** September 21, 2005, 02:26:04 PM »

that all depends on how radical you are willing to go. Stock I think about the widest you can go without running into issues is probably 140 and that may need offset sprockets and probably a new wider rim. If you go to a 16" rear rim and DOHC swingarm you may be able to get 140 and maybe some 150s under your arse. I know there is at least one member here who managed to get a 160 on a supersport with cbr wheels and it barely cleared the frame and swingarm. I think the limit of your k2 frame is probably 140/150.

Guys running 1977-78 motors in rigid frames have been able to get 180 rears under their bikes but that is custom frame territory.

There have been 200+ tires under a cb750 but those are jackshaft bikes and not stock frames at all.

You probably want to post this over at hondachopper since those guys deal with this question on a regular basis.

Personally, there is no reason whatsoever to have a wide tire on a 58hp bike. Espically since it will cut down your useful load and will probablt play all kinds of hell on your tranny. These engines don't have the torque of an hd. A wide tire really doesn't fit the character of the bike, what with wide tires being a modern fad and the biek being 30+ years old now. If you want a wide tire build a harley clone, if you want a cb750 build something useful.

ProTeal55 · « **Reply #4 on:** September 21, 2005, 02:43:01 PM »

A 140 would be fine by me.....

I nevre said I wanted to put a 300 ont he bike , I was jsut posting some pics.

KYRE---> I am not a fan of the 200 and up wide tyre craze. Just looking to put something alittle wider on the back , thats all...

Egil · « **Reply #5 on:** September 21, 2005, 02:51:08 PM »

The 225 and the 300 looks like it`s stands on (and looks great on a) H******* D*******

But seartenly not on HONDA

Egil

ProTeal55 · « **Reply #6 on:** September 21, 2005, 03:38:53 PM »

I know it's not a HD , and I am not trying to turn it into a HD
It's a Honda , I am aware of that.

Egil · « **Reply #7 on:** September 22, 2005, 02:44:22 AM »

You defently already have a w e r y n i c e

bike
And l do understand your searc for som ++ tire.

Egil

Geeto67 · « **Reply #8 on:** September 22, 2005, 03:49:42 AM »

Chill proteal, a lot of guys get kinda funny about the wide tire thing. Personally a lot of people gave me crap for running a 150 rear tire on my 74 kawasaki roadrace bike.

With these bikes putting a 140 or 150 on the rear will really make the rear end look larger than it is. The larger cross section really fills up the rear fender. The cb750 is a much smaller bike than an harley so a big tire on the rear will look really big.

Incidently I went to a mostly harley bike night last night an most of the guys were cool with my bike except one guy who used to own a 1970 cb750 (until about a week ago) who keeps telling me his heritage softail will "absolutley dog" a cb750. I told him let's run em right there and he backed down quick. Some people.

SteveD CB500F · « **Reply #9 on:** September 22, 2005, 04:15:28 AM »

I ride my neighbour's Heritage Softail Anniversary (1450) occasionally. It could keep up with my 500 in a straight line as it has loads of low-down grunt. Just don't try anything fancy on the bends.

Other observations:

1. You don't really need a gearbox for trolling around town
2. The screen cut right accross my vision - I had to either stretch up to look over it or crouch down and peer through it
3. When stopping at lights or junctions, be very careful about putting feet down as a miscalculation here is embarrassing and expensive!

KB02 · « **Reply #10 on:** September 22, 2005, 06:18:42 AM »

Quote from: kyre on September 21, 2005, 02:00:46 PM

which look sooooooooooo lame.

And they don't handle for crap on any road with a little bit of an off cabmer slant (like most of the roads in the northeastern US, slanted t allow rain water to run off more effectively). They're so wide that they are constantly trying to right themselves up against the surface they're riding on. hence, if you have a nice straight road with a bit of an angle to it, you have to fight the bike to keep it in a straight line.

Personally, I still think they look cool, though.

ProTeal55 · « **Reply #11 on:** September 22, 2005, 06:25:22 AM »

Thanks for all the feedback.

Like I said before , I am not a fan of anything over a 200 rear tire on A N Y motorcycle , their is just no point. I ride 300 and even some 330 and 360 tire bikes at work , and they are more than a handful to say the least.
I think a 150 would look cool under the bobbed rear fender of my CB, but with the bike allready being lowered by 1'' , should I have to worry about the tire bottoming out ?
Would I be better off going with a 140 to be on the safe side ?

All of my friends who ride with me , minus two have HD's or some other sort of American V-Twin bikes. I am included because I also have a RoadKing myself. Whenever we ride to a show , and I am on the Honda , I always get the one HD guy who looks down his nose at my bike, because it is not a hd , then I see him get into his Toyota truck and drive off ! !

dusterdude · « **Reply #12 on:** September 22, 2005, 06:41:22 AM »

ok,here`s the lowdown.i put a 5.10(about 130) 16 on my bike.i had to move the brake anchor arm over about a 1/4 inch and had to cut the inside part of the chainguard out where it rubs the tire at the front.no biggie really,but i dont see how you can go any wider without major surgery.

lrutt · « **Reply #13 on:** September 22, 2005, 08:14:24 AM »

I have a 130 on my 76k model and it just rubs the chain guard lightly. That's an 18" BTW.

ProTeal55 · « **Reply #14 on:** September 22, 2005, 09:07:16 AM »

The chain guard has long been removed from the bike , so that's not an issue .
The rear wheel , which is a 18'' , sports a 120 at the momment...

So a 130 is the widest I can run without major modifications ?

dusterdude · « **Reply #15 on:** September 22, 2005, 10:50:27 AM »

absent the chainguard and the anchor arm i seem to remember there is more room as far as the chain and swingarm are concerned.

Geeto67 · « **Reply #16 on:** September 22, 2005, 01:03:26 PM »

the brake anchor is not major surgery, just bend it out in a vice and put some spacers on it and use a longer bolt where it meets the drum. If you want to make a new one I'm sure you could get all you need from home depot for under $20. Since I ditch the chain guard on all my bikes except the bone stockers, i didn't even think of it as an issue.

130 is abut all you will get out of a stock rim. If you go to a 16" harley rim the rim will be wider (I think either 3" or 3.25" can't remember) and shorter so it will give you some drop in the rear and more room to work with on your existing suspension height. If you wanted a real 40's look put a 16" on the front also (most pre war harleys and post war pre 60's pan heads are set up like this). All that sidewall makes the ride a little nicer too, though expect ti to wallow in turns if it doesn't already. Lowrider tommy on the honda chop board can hook you up with the spoke kit and rim (so can buchannan) and recommend a decient tire size.

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