Largest possible tire for the Large Mini Baja bikes

#1
I recently purchased the 21x7-8 tire and found it to barely squeeze into the frame width wise on the rear... Actually there is a ton of space left over for the frame but the rear sprocket is the limiting factor. This tire inflates to 7.75 inches wide and leaves only an 3/16 of an inch clearance to the tire.

https://www.amazon.com/gp/product/B01MRLBXVI/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1

On the front there is absolutely no problem and we could go slightly bigger if I could find a tire slightly bigger In this picture the front tire is the original OEM tire and the rear is the new SUNF 21x7-8 tire ### BAJA DSC_5841 BEST2 cropped-.jpg
 
#3
That just tells me I should put a reverse transmission on it and learn to ride backwards.

Seriously, You really made me chuckle as you reminded me of the hilarious comedy of me trying to mount the tire by myself and then
I took it to a tire store and they also had some significant difficulty and they did not charge me at all because of the trouble.

Then when I discovered it on backwards I did not have the heart to have them redo it. So I said screw it. My reasoning is
that traction is created more so in one direction and when mounted according to the arrow you have more traction going
forward. Since the tire is mounted backwards I will now have more traction when braking so that is not all that bad.
 
#4
There are (at least) a couple of reasons why some tires are directional. First, tread pattern. Street tires designed to evacuate water from the contact patch to decrease/prevent hydroplaning; can be very dangerous mounted backwards. Off-road tires designed to be "self-cleaning", dirt/mud/etc pushed to the sides to avoid tread clogging; reversed, it would tend to pull dirt/mud/etc to the center of the tire. The second reason is internal construction, direction plies are wrapped, etc, usually only applies to high-speed tires.

I have mounted 6" and 8" tires in addition to motorcycle tires using only soapy water (lube) and 3 tire spoons. Tires are not as difficult to mount as most people think, but you need to understand the basics. The main mistake people make is not properly utilizing the drop center. The OD of the rim flange is greater than the ID of the tire bead, obviously, to retain the tire on the wheel. You have to utilize the drop center to mount the tire. If the drop center is offset to one side, you need to mount the tire from that side of the wheel. I'm linking a TireRack article that explains what I'm referring to; it's about mounting/demounting car tires but the basics apply to any tire.

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=314
 
#5
Charles S. Yes all helpful hints are appreciated especially tire mount 101. But did you read that the pros
at the tire shop had a difficult time. This tire happens to be six ply and very very stiff. I suggest you get one
and mount it just for the fun of it. I even bought the $45 HarborFreight tire mount machine which worked
on my riding lawnmower tires. Anyway, like I said, I expect my braking in mud will be improved..
And KUDOs for the sharp eye to recognize the backwards mount. Bravo.
 
#6
I should add as seen in the picture the bottom chain rubed slightly on the frame so I raised up just the rear of
the motor by one inch using washers to create more clearance for the chain. THAT made me have to fabricate
different length brackets for the muffler AND had to re-engineer the reinforcement bracket from the motor mount
to the back of the jackshaft frame since I raised the motor an inch.
 
#7
I should add as seen in the picture the bottom chain rubed slightly on the frame so I raised up just the rear of
the motor by one inch using washers to create more clearance for the chain. THAT made me have to fabricate
different length brackets for the muffler AND had to re-engineer the reinforcement bracket from the motor mount
to the back of the jackshaft frame since I raised the motor an inch.
I imagine you could have modified the jackshaft plate, slotting the mounting holes, and rotated it, raising the jackshaft, rather than raising the engine. People have done that with a TAV/CVT/TC, should work the same for an engine-mounted jackshaft plate.

https://www.oldminibikes.com/forum/index.php?threads/want-to-put-a-tc-on-a-coleman-ct100.141989/

https://www.oldminibikes.com/forum/...ith-predator-212-and-torque-converter.103977/
 
#8
Very kind of you to tell me …. AFTER THE FACT :)

Damn I hate it when I miss the easy solutions.... Usually from over thinking the problem.
 
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