These are Foam tire versions of the OPEN RC F1 rims that allow you to run Tamiya F103 Front and Rear Foam tires.
the 2017 update for the F1 uses wider rear rims.there are 2 types of rear rim width the narrow is designed for the original version of the OpenRC F1. you will need to trim the rear tamiya tires slightly narrow if you want to keep the original width of the rear tire. There is now a 40mm Version of the rear rims so you can install a Full size Tamiya F103 rear tire for more grip. and a slightly wider wheel Track.
There are 2 Rear rims, one is for the Gear Diff from tahustvedt:
The second is the standard rear
The front Tires are Narrow to fit both the narrow Tamiya F103 wheels and also the front suspension conversion from rhoagland:
the narrow fronts will work on the standard front as well.
Print .2mm no supports needed.
*note: i stamped the goodyear Eagle logo on the tires. tamiya tires are blank without a logo on them.
added 40MM rear rim with 3mm inboard offset so you can use a full size Tamiya rear foam tire and it clears the differential gears.
this will increase the rear track of the wheels by 6mm overall (3mm per side) the new tire size is 6mm wider per side adding more rear traction. overall Width is about 177MM with this 40mm tire. 2015 R.O.A.R rules allowed for a total of 190mm of width making these still legal.