Tried it with the slightly larger slicks on the rear, and its probably a bit too fast. Hit nearly 40 mph, on the uneven concrete in our parking lot, it feels very floaty / not planted at that speed. With more traction on the slick tires the turning is worse(the inside rear tire must slip to allow turning).
Will probably look into purchasing a larger section of 10" PVC to use instead of buying precut pvc