I've already created a thread detailing my experiments on this subject since I've found some good alternate rims for the ES and SX to replace their stock rims with others that give better tire choices..
Anyway, for the ES I found the ITP Steel 12x7 Rim, 2+5 offset, and of course on the 4/110 bolt pattern..it's a perfect bolt on for the trike both front and rear. The front offset is spot on centred in the forks so no need to spacer!!
Then with the tires since you have a 12" rim..the choices are endless!! It's totally open to experiment with tires and tread patterns til your hearts content..
I chose these rims in black in my 'Back in Black' project, then for the front tire install a 26x8x12 Bear Claw..the rear got 26x12x12 MudSharks. The Bear Claws are definitely not too agressive, but we did the same update on my brothers trike and he chose Executioners..now they were really heavy and a bit over the top in my opinion. But he likes them just the same!
The bonus part of this is the improvement on the steering and handling of the machine!! Amazing mud and rough trail rider, but still you can sit in the saddle all day long comfortably!
Total cost on the entire project was around $400 shipped from Rock Mountain..don't forget to order 3 sets of tapered nuts since yours is an 85. The replacement rims need tapered, not the stock flat nuts!
Have fun with it and post some pics..several other members have followed suit and there are some cool setups out there using this blueprint!
Here's my project trike from last year to get a visual idea..looks awesome and it's an animal in the mud!!

Last edited by dougspcs; 10-08-2013 at 10:46 AM.
Current toys..
1986 Honda 350X..trail bomb!
1985 Honda 250SX..my main mudder
1985 Honda 250ES..Back in Black Trike
Current non-trike toys:
1990 Honda TRX300FW
1995 Seadoo GTX
1998 Polaris Indy Lite 340(Nearly new looking)
1998 Polaris Touring 500
1998 Club Car (electric)