The tiger is the second largest genus of big cat. The largest species of big cat is the liger, the cross breed between a lion and a tiger. Cool isn't it.
The liger does not count, as it is a man made hybrid. The largest race of tiger is the Siberian Tiger on average, but some Bengals may grow as large.
But that is a special kind of breed so a lion is the largest big cat is 500lobs or more and when it stands up it is 10.8 ft