ok, this is a question that doesnt get asked often im sure. if my truck had a larger engine, i wouldnt even worry about it but my tacoma is a 4 banger. so heres the situation. stock tires on my truck are 245 75 16 dunlops. i checked out the weight of them on tire rack and it was 34 lbs. i was thinking of going up a size to 265 75 16s, a hankook tire that weighs 40 lbs each. i know the difference is only 24 lbs, but thats not carrying weight, thats rotational mass and ive been told that changing the weights of wheels/tires will be noticeable. im not sure how noticeable 6 lbs per wheel would be though. my truck is stock, 2.7L with a 4.10 rearend and a throttle that sticks all the time and makes me drive out of control(sorry i couldnt resist). think 6lbs per wheel will actually be a noticeable difference? i dont wanna downshift everywhere just to maintain speed. i read a couple places online where people said they had to regear but they were also running load e tires, that weighed something like 20lbs more per wheel. anyone have input on this?
suppose to be 1lb of unsprung or rotational weight is = to 6 or 7 so its like putting 150 lbs in the bed of your truck… thats what i was told a long time ago.
Rotational mass, I was always more confident with more rubber 
i went from a 275/60/16 Long trail tire to a 255/75/17 mudd terrian tire. thats a gain of 2.5" of tire mass. I still have stock 342s and a 4.3 v6. ill say i can deffently notice the weight of the tires. i never weighed the two but the MTs are deffently heavier