I read somewhere that if you install bigger tires, you need to replace the brake lines because they will swell and can brake. I have no idea if that is true. It is an 04 FX4 with 2 1/2 level kit. I put on some 315/70/17 (35) on 17x9 eagles. Thanks for any help,

 

The only possible explanation for what you heard is that bigger tires will require higher brake fluid pressure to create the same stopping force (due to the increased tire radius creating more torque). IF you have flexible brake lines that are already marginal and getting close to failing, this could lead them to fail right after you change out the tires. With a 2004 FX4, I would think the brake lines are probably in good enough shape that it shouldn't be an issue.

However - if you are going through the work of upgrading tires and lifting and whatnot... it might be good to upgrade to Stainless steel flex lines. This will reduce the absorption of the lines and give you better response on the brakes (more important with bigger wheels). But if you don't have the money to upgrade right away, I don't think its a big deal.

 

I have 35's with the AS 2.5" kit and I have no issues with braking. It isn't a sports car and I don't tailgate, so I shouldn't ever have an issue with it. I also have the carquest blue pads on the truck and they are super low dust and I think they grab better IMO.

 

i just heard you have to make sure with bigger tires that they dont come in contact with the brake lines...i have 35's with a 2" level and no problems to date (knock on wood)

 

I would be more concerned with the beating your balljoints are going to be taking running the larger tires