Rusty is right; 9" drums together with 13s ARE fine together.
The point I was trying to make was that those 4 piston jobs will be able to lock up the 13s at say hiway speed, and whatever car they are on does not have ABS, so around and around it will go; where she stops, crashes, or destroys peoples lives; nobody knows.
Yes I have driven old Mopes with 13s, owned several of them, I got my Driver's License in 1969, and there were lots and lots of entry level Mopes with 13s in those days. And you just know how I drove at 16.............
Less than two years later, I had earned the nicknames of Ditcher, and Crash.
