Discount Tire Direct (via eBay) has a $100 off Purchases $400+ w/ code CMOTORS0314. Shipping is free. Offer is valid through March 16.
http://stores.ebay.com/Discount-Tire-Direct

You can also stack a manufacturer rebate on top of this.

I bought my tires from DTD via eBay and got a DTD rebate and a Hankook rebate.

I was emailed a DTD invoice/receipt when I bought them.

Current DTD Mfg rebates:

Goodyear up to $80 - Promotions - Discount Tire Direct

$80
Wrangler All-Terrain Adventure w/Kevlar
Wrangler MT/R w/Kevlar

$60
Wrangler DuraTrac

$40
Wrangler SR-A

Cooper - up to $80: http://www.discounttiredirect.com/pd..._8Btz3_i9S_0_0