9XL on 16 cells..what sort of performance?

[Rtsbasic]

I'm still using stock wheels/tyres, do you think the RPM nylon 14mm wheels will hold out? I was planning to purchase some of these as they make the truck a bit wider and are pretty impact resistant.

What sort of speed would I be hitting on 16/51? I think I'm getting a pair of 18t and pair of 20t pinions, would either of these work okay on 16 cells?