No mate, 1" WIDER is the rule, you are thinking diameter.
A 16" rim might have the right profile tyre to make it the same as the stock 14" wheel with stock tyres when it comes to diameter. This is "legal" as long as the wheel is 6.5" wide and no more. Although the TRX has 6" wide rims stock, insurance companies seem to have the info on their system that the rims are 5.5" (they are on every other U12 & UA, bar the TRX and Ti Super Hatch which has TRX rims).