we have tons of 195/65-15 and 206/65-15 gravel tires, in soft and medium compound. Michelin, BFG, Yokohama, Pirelli, Hankooks heh it's like a freakin' tyre store in the barn.
$25 to $50 each depending on tire brand and wear levels. most are 60% or more tread remaining. great for fun use, not so good when you want to win rallies.
these gravels are marked 'for competition use only' and will NOT work in snow. try em in winter, you'll see (bring a tow strap tho!)
LMK how many you want, I'll get em from Bangor to Camden for ya.