Going over 6 inch step with 12 inch wheels

[Biff]

We had the same issue, with more mass in the rear to counter the Big ball when on the arm. Our bot can best be described as looking like a Bobcat. Arm piviots at the rear. The only way up (and we never did it in a match) is to extend the arm after the front wheels are on the platform, shifting some mass to the front tires. Then it climbed very smooth. BTW we are using the 3" tires on the kit wheels which makes a 14" wheel when all is done. This is a tire and tube that comes from Skyway.