I know that Dexter makes axles with different offset angles for their torsion units... I can't remember from memory but have purchased and installed them. . the ones I wanted weren't in stock and I had to wait for a stock order from my distributor so I didn't have to pay freight...
My current 5er has spring axles but I really wish it had the torsion units... On my 5er I had close to 3" between the stock trailer tires... I looked on line at the tire data guide book and found a commercial tire with the right profile to replace the trailer tires... just a little larger in diameter so no I have about 2" between the tires...
I've had the commercial tires on the trailer now for 18 months and I'm guessing 12K miles and you can't see any wear... the key reason I moved was that I picked up 750 # of additional tire capacity per tire... if you read the side of a commercial tire... that given pressure and weight rating is not the max. as it is in passenger car tires. . its a guide... for commercial tires you go to the manufacturers web page and they spell out capacity and pressures... Its raining like crazy right now as I sit here at Bonneville Fish Hatchery or I'd go get the size for you... . But I'm very pleased...
The other thing I changed was to install shocks on these axles, so between the tires and the shocks things now ride somewhat better than what we used to see... . I'm sure it a harder ride... with the commercial tires, yet I know we've stopped some of the bouncing with the shocks...
Hope this helps...