'74 jackpiner maximum tire size

[azrider]

What is the maximum rear tire size you can use and still install the chain guard?

[Kip Kern]

I wouldn't go larger than a 4:00 x 18"

[Scott Summey]

Az,

I just installed a set of Michelin S-12 tires on my 74 Jackpiner. Size is 90/90/21 front and 120/90/18 rear. They fit well with clearance for the rear tire, most recommendations from the forum point to Pirelli MT-16's in size 110/100/18 rear as a good fit also giving a nod to durability and period correctness.

Scott Summey
Jacksonville, Florida