Well, if they can go 60 mph, just run them flat out and then put the maintenance in when you get there. (assuming that op time per work hour is independent of speed)
I would not be wanting to try and do a lot of maintenance on a clapped out tank that had just been driven hundreds of miles to Emu Field - there’s a reason they set off nuclear bombs there - because it was in the middle of nowhere with absolutely nothing of value to be damaged. The nearest road (and that is an unmade dirt road) is 120 miles away. The nearest human settlement (a town of 2000 people, most of whom live underground because of the heat) is 150 miles away. And that town is 500 miles away from the nearest city.
Just for fun, I’ve just used my navigation software to tell me how I should drive from where this tank was (Puckapunyal Army Base in Victoria) to that nearest town to the nuclear test. It’s about a 1000 mile drive, and could be done nowadays - nearly 50 years later when we have much better roads - in about 18 hours in a car. Even if the tank could match that all the way without breaking down, figure at least 21 hours to get to the test site, and if you need four hours of maintenance for every hour you drove - 84 hours maintenance. I’d say it was just a lot easier to transport it the way they did it, and a lot less labor intensive in the end.
Well, if they can go 60 mph, just run them flat out and then put the maintenance in when you get there. (assuming that op time per work hour is independent of speed) You can only keep that kind of speed up so long, then you begin to lose the track's end connectors, which are held on with a threaded wedge and a single 5/8" bolt that are subject to wear and vibration.
One quickie cure if you're around a saltwater beach [ocean or Dead Sea] is to take a mile or so run through the salt water on one side, followed by a return trip with the other track. In a day or so the end connector bolts will rust up pretty good, but vibration and fatigue eventually takes its toll.
The other problem trying to run at that speed is steering, which with a cross-drive transmission, gets pretty antsy in an M48 or M60. I saw an MP Jeep that suffered pretty bad after trying to roadblock an M60 running down a mountain pass road at around 55-60 MPH. If you keep the tank in gear, [automatic transmissions in US tanks since the M47] you chance the possibility of losing braking control. If you drop it into neutral, you lose your engine braking, and can lose a track if you even try to steer in the slightest.
Installing a track end connector
Track end connector wedge and bolt removed.