No you do not need to regear for 35s

 

On my 2010 6 speed i went from the smallest tires ever to a 33" (went up 6 sizes to get there). Ive also got the tow package and resulting 3.73 gear ratio, and going to 33s wasnt really unbearable, however i did find that i wasnt able to maintain speed in 6th and sometimes 5th gear going through the mountains. Ive now gone to 35s, but ive got some shiny new 4.88 gears waiting to be put in as well now. I say just save the money and go straight for the 35s