Crazy dodge

1995 dodge ram p/u 1500/ 5.2 auto 4x2sport slt laramie-- it has 245/75/16 goodyears including the spare but the door sill sticker says its a 225/75/16 equiped truck. these are the two optional sized tires for this truck. i know the trucks history since it has been in the family from new. this is the tire that was on it from the dealer, i think it would be more appropriate to run the 225’s cuz its a 2 wheeler/ sport. will this be a huge change in the speedometer? what kind of job is it to get and replace the speedometer gear/ and to match it up with your specific application?

There will be able a 4% difference in the speedometer and effective gear ratios.