Those type of steering wheels won't crack. Common problems with those are either worn off grain finish or that some get sticky. (and I mean STICKY!) Some do, some don't. I've had one hanging in my garage that literally dripped brown ooze for years!
If no one else answers on the rim size, I can measure one of the 4 that I have. (BTW, If you are looking to buy, I have 3 black, 1 very dark gray in my collection w/caps & hardware-$50 each)
The rim is thicker than the stock truck wheels but not real fat like most of todays cars. This wheel is a bolt on to these trucks. All the horn parts that go with this wheel will work.
Can't help on the tach, I still have to do mine yet...
