I have a 62 with the four-speed transmission and about 33 inch tires. A couple times a year I take it on 100 mile trip on the highway and I get up to around 60-62 according to the GPS. The engine is a 235 and it winds up around 3000 RPM. I have 455 gears in the rear end, as it is a three-quarter ton. 55 or 60 is really no problem.
