Tire Concentricity

[DubP]

All the cool kids are running 10 inch motorcycle tires on 14 inch ebike wheels. So I ran out and bought some Bridgestone Hoops for my scooter with 14 inch wheels. The tire size is 2.75-10. they seem to fit, the front is fine, but rear is not concentric, meaning it has a lot of up/down run-out. You can see that it's not seating evenly by the little bead line on the tire by the rim lip.

I have spent a lot of time trying to see if maybe the sizes are not-so compatable, but is seems like it should be ok. The bead seat diameter (BSD) for a 14 inch ISO bicycle wheel is 254mm, and as far as I can tell, this is the same dimension that designates motorcycle tires, so my 10 inch tire BSD should be 254mm.

So far I've deflated the tire, lubed it up with dish soap, made sure the tube is not pinched in somewhere, ridden it with low pressure, reinflated, etc. but I still can't get it to seat concentrically.

Has anyone else experienced and conquered this problem?

 

[Chalo]

Because bike and riding toy rims were never intended for tubeless or DOT type tires, the internal shape may not be compatible with the beads of motorcycle tires.

If the rim that won't seat is the same kind as the one that seats OK, then you should persist with soapy water and modest overinflation (not over 60 psi) until the tire pops into place.

 

[lnanek]

How wide are your rims? Previous attempts at motorcycle tires and tubes on bicycle rims suggest the rim needs to be quite wide. Like 1.85":

19" Motorcycle Wheels vs 26" Bicycle Wheels (rim and tires)

are you intrigued by the fat tires and beefy rims of motorcycle wheels like this? (image borrowed from http://voltriders.com/ until i get my own done): there's been a lot of interest lately in 19" motorcycle wheels for ebikes, but a lot of confusion because measurements are different for each...

endless-sphere.com

Also mention tire and tube should be from same company due to size variance between manufacturers.

 

[99t4]

BTDT, sometimes tire pliers are required:

PTS-1 Tire Seater

Provides extra grip and leverage to easily seat stubborn tire beads.

www.parktool.com

Agree with the above post, this problem occurs more frequently with wide tire/narrow rim combination. Also, some tire mfrs products fit tighter than others. Schwalbe tires, for example, are often harder to seat.

And if you have run the tire for some time in the non-evenly seated condition, the tire can take a permanent "set" that deforms it to the point that it will never seat correctly and evenly.

 

[amberwolf]

As long as the bead has not already shaped itself to the rim, you mostly deflate the tire, then use zipties perpendicularly wrapped aroiund the tire and rim between the spokes in several places around the wheel to pull the tire into place on the rim evenly, so the bead is evenly seated and it will inflate round. Then slowly inflate the tire, watching the bead to make sure it stays even. Anywhere it expands away from the rim, tighten the zipties in that area (the procedure is something like truing a wheel's spokes). Once it's fully inflated, just leave it that way overnight, if the ambient temperature is warm the rubber will deform at the bead seat until it matches the bead seat of the rim and stays in place. (if it's cold it will take longer for this to happen).

After it's molded itself to shape, the zipties can be removed, and the wheel should from then on be fully round (assuming the tire itself is made correctly and the wheel itself is true)

 

[DubP]

Thanks for all the advice. I think the comments about the rim bring too narrow were correct. It's a very narrow rim compared to whatever 50cc scooter wheel the tire was intended for. And yeah, the ebike wheel doesn't even seem to have a lip, the inner walls are just straight. All that said though, I kinda solved this problem by replacing the inner tube. I bought 2.75 to 3.0 size tubes, but I think since the rim is so narrow they were too big. Swapped it for a 2.5 width tube and the concentricity problem is almost gone. Maybe I just got lucky on the reinstallation, but I definitely think the smaller tube helped as well.

 

[DubP]

One more note on this issue. I recently figured out that yes, there is a bit of difference in bead diameter between the 14 inch bicycle wheels and the 10 inch scooter tires. While this allows the possibility of the tire seating in a non-concentric position, it seems like the tires generally want to seat evenly. UNLESS the bicycle rim is very narrow. This was my issue. Between the valve stem and the two inner tire beads, there just wasn't enough width and the tire would always seat with the valve stem end pushed a bit further out. When I used crappier tubes with narrow valve stems, the tire mounted concentrically every time.

 

[qwerkus]

Schwalbe advise to use lube all around the tire seat. Then slightly overpressure and the tire will jump right into the correct position. Only works with new tires and flanged rims.