Major noob question

BionicOnion said:
So...how do I know how wide a tire I can fit on a rim? Like 120mm on a standard width bmx wheel?
Click to expand...
Regular BMX wheels are 100mm wide at the front axle, 110mm wide at the rear. Most BMX frames these days will take a 2.4" tire (61mm) without complaint.

If you're just talking rims, well 35mm is pretty wide for a BMX rim, and offers plenty of support for a 3" tire (76mm).

All 4" and wider bicycle tires ride like crap, roll like crap, weigh a ton, and puncture easily. It's a pass-fail IQ test for those who can't pass the regular kind.
 
BionicOnion said:
So...how do I know how wide a tire I can fit on a rim? Like 120mm on a standard width bmx wheel?
Click to expand...
In addition to chalo's reply:

How far apart are the forks or stays at the point they intersect with the tire location?

If it's in the rear, where does the chain pass the tire, at the lowest gear?
 
amberwolf said:
In addition to chalo's reply:

How far apart are the forks or stays at the point they intersect with the tire location?

If it's in the rear, where does the chain pass the tire, at the lowest gear?
Click to expand...
Forks and stays are going to be built to whatever size I need. Im just curious if physically they can be mounted safely

I have 2 sets of rims i can use from donor bikes, one diameter is good for 12 inch sized tire and the other is a 20inch bike set so 16 inch or fat bike tires, I guess I've never thought about bead width surfaces or things of that nature prior to this. Im trying to figure out if either will work and if so which would be better. Or if neither will work and I should find some fat tire wheels or moped rims
 
Last edited:
BionicOnion said:
I have 2 sets of rims i can use from donor bikes, one diameter is good for 12 inch sized tire and the other is a 20inch bike set so 16 inch or fat bike tires,
Click to expand...
FWIW, bicycle rims / tires are sized differently than MC or moped ones, so a 20 inch bike wheel uses 20 inch bike tires, the wheel is specified by the size with tire on, where MC/moped is specified by rim size. There are several sizes of 20" bike rims, though, so measure it to find out which one it is.

If it's the common BMX size (see the sheldon brown site or wikipedia on bicycle wheels for a rim size chart) then you can even use 16" moped tires and tubes on it, as I do for trhe rear wheels of SB Cruiser (which are 406 x 40mm wide rims) --I use the Shinko SR714 16x2.25", but they make a version up to at least 3.5" (it's labelled in mm though,, like 90/80-16). I prefer them because they are much thicker treads so they are more puncture resistance to the crap on the roads, and stickier compound than the typical bicycle tires in this size.

SR714 Tire

Designed as OEM replacements for moped models.
shinkotireusa.com shinkotireusa.com

endless-sphere.com

16" Motorcycle Tires on 20" Bicycle Rims

I know it requires a good bit of wrestling to get 16" motorcycle tires on 20" bicycle rims, but I've never seen any discussion as to whether or not the width of the rim makes any difference. I've seen videos of people struggling to get motorcycle tires on 100mm wide rims, but it looks a bit...
endless-sphere.com endless-sphere.com
 
amberwolf said:
FWIW, bicycle rims / tires are sized differently than MC or moped ones, so a 20 inch bike wheel uses 20 inch bike tires, the wheel is specified by the size with tire on, where MC/moped is specified by rim size. There are several sizes of 20" bike rims, though, so measure it to find out which one it is.

If it's the common BMX size (see the sheldon brown site or wikipedia on bicycle wheels for a rim size chart) then you can even use 16" moped tires and tubes on it, as I do for trhe rear wheels of SB Cruiser (which are 406 x 40mm wide rims) --I use the Shinko SR714 16x2.25", but they make a version up to at least 3.5" (it's labelled in mm though,, like 90/80-16). I prefer them because they are much thicker treads so they are more puncture resistance to the crap on the roads, and stickier compound than the typical bicycle tires in this size.

SR714 Tire

Designed as OEM replacements for moped models.
shinkotireusa.com shinkotireusa.com

endless-sphere.com

16" Motorcycle Tires on 20" Bicycle Rims

I know it requires a good bit of wrestling to get 16" motorcycle tires on 20" bicycle rims, but I've never seen any discussion as to whether or not the width of the rim makes any difference. I've seen videos of people struggling to get motorcycle tires on 100mm wide rims, but it looks a bit...
endless-sphere.com endless-sphere.com
Click to expand...
Thank you for your experience and knowledge AW. The 2 donor bikes i have are a 16 inch and a 20 inch so actual rim sizes would line up for a 16 inch moto tire or 12 inch moto tire in terms of rim diameter. My confusion is if the wheels which each only appear to be visually about an inch or so wide, can that and how does it support a motorcycle tire bead? I'm looking at building a tadpole with custom front mounts, so width doesn't matter as much. Im more concerned about better lasting tires for reasonable pricing
 
BionicOnion said:
Thank you for your experience and knowledge AW. The 2 donor bikes i have are a 16 inch and a 20 inch so actual rim sizes would line up for a 16 inch moto tire or 12 inch moto tire in terms of rim diameter. My confusion is if the wheels which each only appear to be visually about an inch or so wide, can that and how does it support a motorcycle tire bead? I'm looking at building a tadpole with custom front mounts, so width doesn't matter as much. Im more concerned about better lasting tires for reasonable pricing
Click to expand...
Excuse me it I am misunderstanding your statements.

This is what I understand about bicycle and motorcycle tires etc...

Bicycle tire sizing is unusual in their nomenclature in that they are loosely based on the overall diameter of the tire not the rim diameter.
For example a 16" outside diameter bicycle tire can possibly designed for two different rim diameters !
Usually measured in millimeters the rim diameter for a 16" bicycle tire could measure 305mm (12") or 349mm (13.75")

Motorcycle and car tires are measured by rim diameter.

Here is a bicycle rim chart where ETRTO = European Tyre and Rim Technical Organization
See example of the first line on the chart . . .
16" is the outside diameter of the tire.
Next number, 50 is the tire width.
Following number, 305 is rim diameter.
dimensions-chart-cicumferences.png

Bottom line :
A 16" motorcycle tire does not fit a 16" bicycle rim.
 
PaPaSteve said:
Excuse me it I am misunderstanding your statements.

This is what I understand about bicycle and motorcycle tires etc...

Bicycle tire sizing is unusual in their nomenclature in that they are loosely based on the overall diameter of the tire not the rim diameter.
For example a 16" outside diameter bicycle tire can possibly designed for two different rim diameters !
Usually measured in millimeters the rim diameter for a 16" bicycle tire could measure 305mm (12") or 349mm (13.75")

Motorcycle and car tires are measured by rim diameter.

Here is a bicycle rim chart where ETRTO = European Tyre and Rim Technical Organization
See example of the first line on the chart . . .
16" is the outside diameter of the tire.
Next number, 50 is the tire width.
Following number, 305 is rim diameter.
dimensions-chart-cicumferences.png

Bottom line :
A 16" motorcycle tire does not fit a 16" bicycle rim.
Click to expand...
No, it is confusing. I know the numbers do not line up. I have 2 20 inch bike wheels which will fit 16 inch moto tires, and i have 2 16 inch bike wheels which line up to fit 12 inch mini moto tires. At least as diameter. Im concerned specifically about bead mounting surface diameter. So will a regular width bicycle wheel hold a 3 inch moto tire the same as it would a 2.125 bike tire?

I'm not sure if I'm asking this right to be honest
 
BionicOnion said:
No, it is confusing. I know the numbers do not line up. I have 2 20 inch bike wheels which will fit 16 inch moto tires, and i have 2 16 inch bike wheels which line up to fit 12 inch mini moto tires. At least as diameter. Im concerned specifically about bead mounting surface diameter. So will a regular width bicycle wheel hold a 3 inch moto tire the same as it would a 2.125 bike tire?

I'm not sure if I'm asking this right to be honest
Click to expand...
Besides the rim diameters being different enough to be a fight to fit, the thickness of the beads on the moto tires probably add up to be too thick as well.
If the two parts (moto and bicycle) are forced together how reliable is the end result ?
Does the extra weight and stronger casing of the moto tire damage the light weight bicycle rim and spokes ?

There are charts for matching tire width to rim width . . . for bicycles.
(same type charts exists for moto)

www.lightbicycle.com

Tire Size Chart For Bicycle Rims

Check this rim-width-tire-size chart to find the perfect rim and tire match. For Light Bicycle mountain, road, and fatbike carbon rim wheels. More tire choosing guides included.
www.lightbicycle.com

Going to say, the fit of casing and diameters as an adaption between moto and bicycle is something you will have to invest / try on your own.
 
BionicOnion said:
So will a regular width bicycle wheel hold a 3 inch moto tire the same as it would a 2.125 bike tire?
Click to expand...
No. You might be able to mount it (especially if it's not "regular width" but wider than normal), but the rim won't be wide enough to stabilize the tire laterally, and you'll have to overinflate it to make it behave. If you have to overinflate, you give away the main advantage of the wider tire.

All this goofy nonsense has been tried on bikes again and again and again over the last 150+ years, and just about everything that doesn't look and act like a normal boring bicycle (the winning, iterated design) was rejected because it sucked. So knock yourself out, but I'm telling you now that whatever you're doing, you're most likely going to demonstrate that it sucks.
 
Chalo said:
No. You might be able to mount it (especially if it's not "regular width" but wider than normal), but the rim won't be wide enough to stabilize the tire laterally, and you'll have to overinflate it to make it behave. If you have to overinflate, you give away the main advantage of the wider tire.

All this goofy nonsense has been tried on bikes again and again and again over the last 150+ years, and just about everything that doesn't look and act like a normal boring bicycle (the winning, iterated design) was rejected because it sucked. So knock yourself out, but I'm telling you now that whatever you're doing, you're most likely going to demonstrate that it sucks.
Click to expand...
Haha welll that's pretty clear then. Find the right rims for what your trying
 
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