New 20" Rims and Tires
 

I have a 2003 F150 short bed, regular cab, 4X2 with stock wheel & tires (235/70R16). I have a 4.6 V8 and 3.55 gears. I don't do any towing and must of my driving is city driving. I am interested in performance and nothing else. I am not that concern with mileage either.

I am going to upgrade from my stock wheels and tires to 20" rims. I have two questions.

1. What would be the best tire combination for those rims? I do not like the low profile sport car tires and I want to be able to fill in the wheel opening. The stock tires in the truck now are 29" and I was aiming for about 33". I don’t want to lower of lift my truck.

2. What would be the best gear for above tire combination (depending on your suggestion) considering by driving style. I was thinking of 4.56 gears.

Any suggestions would be greatly appreciated. Thank You.

33" tires on a 4x2 with no lift might be cutting it a tad close for clearance. I'm sure someone else will chime in here on that. What I have is 285/50/20s on mine, which end up at just under 32" (31.8) I have a 4.6 and 3.55 gears. I've kicked around regearing, and if I did, I think I would go with 4.10s. 3.73s would get me about back to "stock" rpms. Check out this calculator - it includes gears, rpm, ring & pinion, transmission gears, and transfer case (for the 4x4 guys). It will calculate final speed.

http://www.4x4wire.com/tech/applications/gearandtire/

Transmission gears are posted in another place on this site for pretty much all Ford trannys - I don't have it saved, though.

Take a look at my pics, if you want an idea what you're looking at for clearance. My truck is lowered 1" in front, and 2" in back (SVT coils in front, shackles in back) The only reason I say the 33s might be close is on the front when turning. Mine are close on the front/rear of the tire, although you might be able to trim a tad and get away with it. You shouldn't have any probs with 33s on top, esp. without lowering it.

Good luck!

Thanks for the quick response and for that link, it was extremely useable. I love the look of your truck.

I am looking for a similar look as your truck, but don’t want to lower it. I am not necessarily looking for 33” tires; I am looking for something that would fill up the wheel opening without any clearance problems and I though that 33” could do the job, but I was not sure. The stock tires look too small on the truck and I definitely want to go with 20” rims so your combination might work great for me.

The truck feels real slow on take off and I feel that it needs more gear. I just need to figure out what sizes is best for my truck and my driving needs/style.

Thanks again.

I have 285/55/R20s on my truck and it fills the fender well out nicely. There is no rubbing.

Yup, 33's are way to big without any lift at all.

Thanks for the kind words . . .

I found another link that you might find useful - I was thinking of it last night, but I couldn't remember where it was. Anyway, here it is:

http://www.csgnetwork.com/tireinfo4calc.html

You can put in tire sizes and it will give you diameter. It also can compare stock to what you want to go to, and tell you how far off your speedo is.

I remembered wrong - my tires are 31.22

The 285/55/20s are 32.34 (and look nice, by the way!) In your sig, though, you list them as 275/55/20 - just a typo? Which one is it? The 275s would be a 31.94 diameter. Either way, a nice looking truck!

Let us know which way you go!

Thanks again

Any sugestions from anyone about gears? If I go with the P285/50R20, which are 2.27" bigger than the stock tires. Which would be the best gears for performance and mostly city driving?

You will be fine just leaving them where they are. Unless you tow a lot. Im running 33x12.5 A/T (with heavy 20x10 in rims) on the stock 3.55 gears and doing just fine.