I used
www.tirerack.com to buy a set of 5 Yokohama Geolander AT-S in a 245/70/17 and the transactions was quick, painless and very cost effective.
They will only accept a direct deposit into their account but as they're in the US that means a trip to the bank and an International transfer.
I did this on the Thursday and the tyres arrived on the Tuesday, 3 working days later. Shipping was around $500 for the lot.
It may pay to bring 2 tyres in and leave 1 as a spare.
Cheers
Tim