Hey I'm not so good at all the tire size stuff and knowing what will fit where so i decided to ask for a little help...I have a 2008 F-250 Powerstroke im running on 275/70/18 right now and id like to go bigger, but i don't know how big i can go...i don't have a leveling/lift kit on it everything is stock...im sorry if this has been asked a million times, i don't really know how to navigate through these forums. I was looking at 35/12.5/17 could i do that? Is it ok to go down a wheel size? I don't want it to rub or hurt anything I just want something a little bigger thank you all in advance **confused girl**

 

Take your truck to a tire dealer & have them measure the with of your rim & they will tell you how wide of a tire you can put on your rim

 

I am kinda in the same boat, all stock 08 F-250. Currently has 275/65 R18 (pizza cutter tires) on it.

I saw another truck like mine that had a stock suspension with 355/65 R18 Nitto Terra Grappler , a LT tread fairly decent look on it.

I do know you can't change the R (rim size) on a tire at all, unless your going with different rim size say 21" you need R21 tires. If your truck is factory the 18" rim was only shipped with one size 18" rim. Unless the dealer got a special on it.

 

I actually ended up fitting 35's on it with no problem and no rub i was a little worried but it worked out great good luck to you

 

35's with no rub, nice! how wide? and that's on your original 18" rims with stock suspension??

Good deal!