I have a 04 f150 fx4 and needed new tires. Stock spec was 275/65 r18 however all the stores in my area had limited stock. Americas Tire told me they had a set just a little taller in my price range and I went ahead and got them. Not paying attention the tires are 265/70 r18. Is this going to hurt my fuel mileage? Handeling?Transmission?? They are just a little taller and narrower. Any one have knowledge?

 

Those are only .5 inch taller, and about .5 narrower. They will not affect your transmission or the any other part of your drive trane as that matters. As far as handling, you are losing a little bit of rubber on the road, prob not enough to matter. Depending on the sidewall construction/load rating they could be a little stiffer or softer - that would reflect in your ride quality. Also fuel milage will depend on the weight of the tire, my guess is you will not see a change.

Do you have the make/model of old tires and make/model of new tires? That would help comparing a little more. Ultimatly I dont think you will notice much of a difference.