Inner tubes !

[JJames]

Whats the deal when buying inner tubes - for my CRF 250 L . I've bought new tires Front is a 90/90-21 . I get that it has to be for an 21" rim , but will a tube marked 80/100-21" work ?
Same goes for the rear 120/80- 18 . Does the inner tube have to be for the exact same size as the tire , (if it's for a 18" rim )? . Thanks !

 

[JJames]

For example , I have orderd a michelin heavy Duty tube online ,they say it fits these sizes : 100/100-18, 110/100-18, 120/90-18, 130/80-18. Does not say it fits 120/80-18. Strange !

 

[Igofar]

On MY CRF250L I don't use Michelin, or any other HEAVY DUTY tubes due to heat issues, and the fact they are more difficult to change trailside etc.
I've been using IRC Tire Motorcycle tubes with outstanding results.
My front part number is IRC-80 (2.75-21) which will fit 275/300, 100/80, and 90/90-21 tires.
The rear part number is IRC-66 (4.00-18) which will fit 400/510, 120/80, 130/90 tires.
The standard tubes are much easier to replace trailside with spoons, and are just as thorn resistant, and pinch flat resistant as the more expensive HD tubes, but without the Heat issues.
Since these bikes spend most of their life on the pavement, doing highway speeds, the heat issue is more of a concern etc.
The most IMPORTANT thing about installing tubes is how the valve stems are installed.
Almost every motorcycle sold has the valve stems installed INCORRECTLY!
This Information is directly from the folks who make the tubes.
When you look at most the valve stems, you'll see SOMEBODY put the little metal washer on the OUTSIDE of the rim, then tightened down the one, or sometimes two locknuts, because they didn't know what they were doing!
The metal washer is designed to seat INSIDE the rim so it contours the correct shape.
The two locknuts are designed to seat against each other to keep the stem from moving, not to tighten down against the rim etc.
Again, this comes straight from several of the tube companies.
Here is a picture that IIRC Michelin emailed me of the correct, and only placement that these parts should go.
Honda, and several other dirt bikes simply have a rubber shroud or sleeve to hold the stem in place, and the metal washer goes inside the rim as designed.
The funny thing is, try telling someone who's been doing it wrong for years (damaging the rim surface with the metal washer on the outside) and they will look at you like a deer in the headlights, and just mumble "I've been doing this all my life, so it must be right"

 

[SMSW]

The funny thing is, try telling someone who's been doing it wrong for years (damaging the rim surface with the metal washer on the outside) and they will look at you like a deer in the headlights, and just mumble "I've been doing this all my life, so it must be right"

Sadly, this goes for ALL the trades. Many of these folks learned on the job and were never given a rational for why they do something but were told to do it 'this way'. Absent a curious mind they never question if there might be a better way or indeed, why a certain procedure is followed. Not everyone is like this, but the 90% that are ruin the image of the remaining 10%.

 

[JJames]

Well I guess I'll have to be there and make sure they /he /she does it right ! Or maybe just get some spoons. If you guys do it on the trail ,I should be able to it in the garage . This is good info for a newbe. I just assumed that the IRC tubes would be cheap stuff worth changing , but I guess not then. Heat won't be a problem here though. How big a gap should there be between the locking nuts and rim?

 

[dduelin]

I think there is some room to disagree about using HD tubes in dual sport or trail bikes. If you look almost all tube manufacturers recommend HD tubes for off road use and these type of bikes the manufacturers typically deliver HD as OEM. Reasons include they are 30 to 50% thicker giving additional puncture resistance and if the tire is run with low pressure for better traction off road the tubes are less likely to have pinch flats when handling rocks, wash outs, and roots. Another reason is if they are punctured they are less likely to split and be rendered unrepairable with a patch kit. Less pinch flats equals less trail side repairs but I agree that Larry brings up the strongest reasons not to use them on bikes likely to see a lot of street riding and that is heat buildup and weight. Bikes used mostly on the street have no need for HD tubes. My last dual sport topped out at 70 mph on pavement so heat buildup wasn’t an issue, getting run over was !!!