I am a bit confused as to what capacity diesel forklift I use for a load as described below.

Load:-
Approximate Max Weight:- 2.5 tons or 2500 kg
Length:- 12 feet {this is critical, load has to be picked and transported length wise}
Width:- 3 feet 6 inches
Hieght:- 2 ft 8 inches.

Could I get some help from someone !!!

Secondly is there any formulae to calculate the de-rating of a forklft depending on the change in the Load Center.

Thanks