I have a 1987 F-150 Custom pickup. It has the inline 6 with a 4-speed manual transmission and 4wd. I was wondering what are the biggest tires I should put on it with stock suspension/no lift at all. I am told that 31's are the biggest that my engine will turn because I drive around town quite a bit and it will start to mess up my tranny/drivetrain/engine if I run too big of tires. I was also wondering how big of a lift anyone would recommend for my pickup. I want to run 33" super swamper TSL/Radials with a 3" suspension lift. What would be my top speed with 33" tires? Any suggestion?

 

yeah billy, theres lots of options out there for lifts. it depends on what your budjet is, whether your willing to dish it out for a good quality lift, or go the cheaper way. rough country makes a 2.5" lift that i had on my truck for a while. worked well, should fit 33's just fine. and yes 31's are probably best for no lift. hope this helps some. oh yeah, and top speed on mine is 90 ish, and i have 33's also with stock 3.55 gears.

 

32's will fit with no lift but they will rub when you flex. You don't want to get tires too big if you don't have the money to swap in new gears also. Your engine tranny and other driveline should be fine for tires as big or bigger than 35's, but it all depends on how you treat it. The only problem you'll have with big tires is not being able to get going if you still have stock gearing in your differentials. You'll probably burn up your clutch too.

 

as long as your clutch is good, you will see little change in your daily driving going to 31's. You probably have 235x75x15 tires stock? I am not a big fan of gear changes unless you have an automatic. Really don't need them unless your rock crawling. But, if you like to take off the line like a bat out of heck, that is the route to go.

lifts are the way to go. if you don't have the money, just stop eating out as much for a month or two and be a tightwad. lift kits for our trucks are cheap. figure about $500 for a 2-3 inch lift and $600-800 for anything over 4". btw, I recommend the 4" lift with add-aleafs

As to top speed, you don't want to be going over 75 mph with 33's. They really flex alot when you get on the brakes and taking turns. But, in all reality, your top speed is only limited by engine rpm and you should still be able to do 100 + if your brave enough (and dumb enough)