Tallest 42 for mud

[sparepartsdave]

I've got a friend that runs his Bronco in mud competition. The rules he runs under keeps him in his class as long as he's running a tire that is called(not measured) 42. He's trying to figure out how to get the tallest(and narrowest) 42 to work under his Bronco. He went to Interco's website an took there measurements, but it wasn't close to what he actually found on mounted tires. He's thinking about putting a 42 Bogger on skinny wheels to get it taller. I know nothing about the mud trucks(I'm building a crawler) but I figured there's enough experience around here that some one would have an answer. Thanks for any input. I'll relay the info to him

 

[muddinmetal]

The 42 is labeled a 42.5. Will that be a problem?