CB350 Tube Sizing Question

BranchW

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May 5, 2024
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Location
Greenville, South Carolina
I am replacing my 1969 Honda CB350 tires and tubes and went ahead and bought everything before taking the old tires off. I noticed that the original tube for the rear tire says 3.50-18 // 4.00-18 but the tube I bought is 3.25/3.50-18. The label on the new tire shows tube type as “3.50-18”.

Will the 3.25/3.50-18 sized tube work for my new tire or do I need to get a different size?

Thanks for any help you can provide!

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I think you'll like those tires. I'm just trying them on my CL350 and they seem great. Good tube choice, better to not have wrinkles from too fat a tube. I use talcum powder not watery soap for my installs.
 
I was always told that when buying tubes, it’s better to buy them where your tire size is at the lower part of the tube size range. That way, when it’s inflated to the proper pressure, it isn’t stretched as thin as one that’s made for a smaller width. So, in your case, a 3.50 - 4.00 tube is what I’d put in a 3.50 tire. But…the tube you bought should be fine too.
 
The reality is, one manufactures 3.50-4.00 is not the same as another's of the same markings. Thicknesses vary also. As I said before wrinkles are definitely worse than a slight stretch, regardless of size marked.
I've seen tire inner casings with the plys exposed from heat and friction where a too fat tube had wrinkles that eroded the inner tyre lining. Too fat tubes are also more difficult to correctly mount and more likely to get pinched under the tire bead edge and won't seat evenly.

I do generally do as you when buying but I trust my eyeballs more than size markings.
 
ballbearian said:
The reality is, one manufactures 3.50-4.00 is not the same as another's of the same markings. Thicknesses vary also. As I said before wrinkles are definitely worse than a slight stretch, regardless of size marked.
I've seen tire inner casings with the plys exposed from heat and friction where a too fat tube had wrinkles that eroded the inner tyre lining. Too fat tubes are also more difficult to correctly mount and more likely to get pinched under the tire bead edge and won't seat evenly.

I do generally do as you when buying but I trust my eyeballs more than size markings.
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Same goes for the tires themselves. Many times, the width marked on the side of the tire is just a ballpark number, and the actual width depends on the manufacturer and style of tire. My answer to people when they ask if a wider than stock 3.50 (or whatever) width tire will fit on their forks without rubbing the fender is, “It depends on the tire”.
 
1969 CL350 said:
Same goes for the tires themselves. Many times, the width marked on the side of the tire is just a ballpark number, and the actual width depends on the manufacturer and style of tire. My answer to people when they ask if a wider than stock 3.50 (or whatever) width tire will fit on their forks without rubbing the fender is, “It depends on the tire”.
Click to expand...
Ain't that the truth! I'd really like to go slightly wider with the rear on my CX and I've got about 5-6mm to spare on one side (CX's are slightly off center due to the shaft drive) and the 120 Shinko on the CB that would be the same exact size(120/90/18) is narrower than the 120/90/16 Kenda on the 79 Custom
 
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