They should have 24/32" on them new, and I'll bet that's right on the money. So 1/8" would be 4/32", so they should be in the 18-20/32" range. You can buy a tire depth gauge at about any automotive store for $2 (US), I love mine, but I'd like to get a durometer as well.
Mine have from 12/32" to 16/32" on them, the one with the hole in it has less wear because I favored it more.
I have no idea as to what wheel washers are used for, sorry.
You should post over on the Jeep BBS, just mention that the Zuki rims are 5.5" wide, perfect for the 32 or 34x9.5 Swampers, and that they clear disc brakes. I'll bet someone will swap.
I don't have any 10" rims to swap, or you'd be welcome to them, sorry. The widest I have is 8" wide.
Are you buying these sight unseen? You may want to confirm with a tire depth gauge they have the amount of tread advertised. If they don't, let the guy know and see if he'll take less, kinda like pro-rating a tire. $745 CDN is $478 US, and since the tires go for $129 each new, that's $516 US, without shipping ($20 a tire US), so they're nothing to get too excited about. I'd offer less as well, just point out the fact they cost about that new. I calculated the exchange rate at http://http://www.x-rates.com/calculator.html
, so it's using current figures.
If you like and want them, and are willing to pay that, by all means get them, they're a good tire. They're also hard to find used, and anytime I can save some $$$, I jump at the chance.
Winter Harbor, Maine
'81 CJ-8 Scrambled, It's a Jeep, Chevy, IHC kinda thing!
'88.5 Zuki, 5" Calmini, Locked, Swamped, Rolled, and just generally broken in right!