Topic: Tire / wheel rim width help

[MarkMadness]

Hi all,

I've got a question about the rear wheel for my '77 CB750.  I've gone through many threads on this forum and can't seem to find the answer I'm looking for, so I figured I'd ask and see if any of you can help me out.

Basically, I bought a Pirelli Route MT66 tire with the following specs: 140/90-16TL 71H MT66 REAR (http://www.petes-superbike.com/1409016tl-mt66-rear-p-2408.html)

Obviously I can't mount these 16 inch tires onto my stock 17 rim, so I'm going to get a 40 spoke 16 inch Harley rim and lace it up with my stock hub. 

My question is, what Harley rim width do I need?  It isn't obvious from the Pirelli website what size rim these should be mounted on.

I was under the impression that I need a 3 inch rim like this one: http://www.jpcycles.com/product/2000000

Can someone help me out here? 

Thanks,
Mark

[Powderman]

A 140/60 is standard size tire for a 4.25" rim. Put that tire on a 3" rim and it is going to crown the profile drastically and affect the handling of the bike. You may also have chain/guard clearance issues with a tire that wide on a proper rim on a 750.

[MarkMadness]

Hi Powderman, thanks for the reply.

Did you mean to say "140/90 is standard for a 4.24 rim" rather than 140/60?

Also, where do you get that sort of info?

Thanks,
Mark

[JWExperience]

It can be done no prob...I put a 150 on my 76 cb750k and just relocated the brake stay to give more clearance. I can't remember at the moment where I found my info but you should be able to google it. My rim is either a 4.5 or 5 prob 4.5, not sure but 4.24 sounds accurate for a 140. Since you have a smaller rim too that will put your tire in a wider point on the swingarm too so you will be good either way I would think. Chain is a non issue on the 77/78's from what I read until you go over 160 or 170 I think.

[klusen]

my 150/60/18 on 4,25 rim needed brake stay relocation + offset sprocket (10mm) for chain clearance. CB750 from 1978.

[MarkMadness]

Awesome.

I'll go with the 4.25 rim then.

Thanks guys!

[lucky]

There are charts that tell you the maximum tire width, for a particular rim width.

[Stoli]

http://www.c-note.dk/wordpress/wp-content/uploads/2013/12/Motorcycle_Rim_Width_Tire_Size_Chart.pdf

I think a 4.25 is gonna be too wide for a 140/90. I have used the chart above before and it shows a 3.5 as standard for your tire.

[Powderman]

Hi Powderman, thanks for the reply.

Did you mean to say "140/90 is standard for a 4.24 rim" rather than 140/60?

Also, where do you get that sort of info?

Thanks,
Mark

I had the numbers wrong. They are correct for a 140/60 and a 4.25" rim. The 140/90 is standard size for a 3.5" rim. Putting the 140/90 on a 4.25" rim would not be a solution for that tire. It would make turn in slower, use a 3.5" rim.

[MarkMadness]

Hi all,  thanks for corrections. I contacted Pirelli directly, and they forwarded me a spec sheet that said the approved rim width for that specific tire was 3"-4".  Now I know for sure I'll be ok with the Harley rim I was looking into. Thanks again