Depends how much spare power you think you have. It's not a simple matter of doing the maths on the rolling radius (diameter) of the tyre and comparing final drive ratios, the bigger tyres also take more turning and can lead to very poor on-road performance and pretty dire off road too once the rims are full of mud.
It's why sports cars have low profile alloy wheels, to limit the amountof mass they have to spin up.
