Hey everyone.......I'm 15 and have a 1999 F150 5.4l 4x4 (w/ off road package) and i need to replace the stock tires soon (has almost 50000 miles on them) and i want to get some bigger stuff than the stock 265/70-17's and i want to know if 305/70-17's will fit without modding or with limited modding (and preferably no rubbing)...i have one more question too, what does cranking the torsion bars do and how do you do it if it's needed?

 

I am looking at bf goodrichs specs for that size of tire the 315's won't fit a rim narrower than 8.5 and I do believe the stock rim on your truck ie 7.5 wide. unless you want to get new rimms you might want to go with the 285/70r17's. those are bigger tires and will fit those rims. pluss I am not sure but I don't think the 315's would fit without a lift.

 

You would not be able to fit a 305/70 due to the fact that is a 35" tall tire. You want to look for 33" tall tire. Thius would require that you crank the torsion bars and if you look around you can find directions. BFG makes a 33X11.5R17 but wider is better and Pro Comp makes a 33X12.5X17. A 12.5 inch wide tire can fit on a 7.5" rim but it usually voids the manufacturer warrantee. You just have to run the PSI a little lower to get better wear. I know guys who run 12.5" wide tires on 7" rims.

 

that is interesting. so you are saying I can put bfg's 315/70/r17's on my 7.5 inch rims. all I got to do is let a little pressure out. does this affect the ride or wear on the tires. dose it make more noise on the highway or any thing like that. I have a lift that allows up too 35's on my truck but didn't think I could fit that tire on my rims because bfg.s specs said the minimum rim size was 8.5. if I do go with thos 34.5 inch tires I will probably have to get me a set of 4.10 gears sets for my rear end and a set for my front differental too so and that can be alot of money to do that. so for now I will stick with the 32.8 inch tires which I can live without the gear sets.

 

I wouldn't recommend putting a 12.5" tire on a 7 or even a 7.5" rim. I'm sure it can be done, but why run lower tire pressure than you should to get OK wear? There's other issues with running low pressure, like heat dissipation and such. I'd stick with a tire that's OK'd for running on your wheel, or buy some wider wheels.
As for torsion bar cranking, that will raise your front end up, somewhere around another inch (depending on where your's are set currently). It'll cost you a new alignment though. Tire-wise, I'd stick with some 285/70/17's. I think they'd look under your truck. Good luck -

Mike

 

I have the 305/70/17 GY MT/R's on my 2000 4x4 and they fit perfectly. There was no rubbing and I did not need to crank my torsion bars. These were on the factory 17 inch sawblade rims. My buddy just stuffed the 315/70/17 BFG A/T's on his 2002 Fx4 on factory rims and all he did was trim the front valence for clearance. He didn't even have to crank the torsion bars for full clearance.

Just my thoughts. They work.