Valencia is keen on leaving The Hammers in search of regular first-team football, with manager Slaven Bilic also happy for the striker to move on, in order to use the money generated to bring in new players.
Valencia, 27, spent last season on loan at Everton, but Ronald Koeman has decided against making the deal a permanent one. The Ecuador international only started five times in the Premier League for The Toffees and found the back of the net three times in 30 appearances during the season in all competitions.
The forward is very popular in Mexico, after impressing for Pachuca before moving to West Ham in 2014.
The opportunity to return to Central America makes Tigres an attractive proposition for the striker and one that could gather pace very quickly as a deal to offload Valencia edges closer with the Hammers eager to kickstart their summer spending.