Will 245 35 18s make a big driffrence for good or bad.

245 40 18 is very close to the stock height. That's what I'm going with.

because how im driving my car my tires might last till 20,000 miles
I have 9600. I love taking theis turnoff by my house leagal speed is 25 i go 70-75 around it its great and it can keep going and going.I once got it up to 83 but the stock tires cant handle any more than that. ( i do this really late at night when no cars are around) Im hoping with the bigger sticker tires i can go higher. I am also thinking of getting etheir front and rear sway bars or i might get an intake first? dont knwo what to do.