I’ve been doing a lot of searching, but not really finding the info I need. I plan on doing a DJM 3/5 drop on my 86 F150 and want to run 20” rims. I’m confused on the width, offset/backspacing I need in order to accomplish this. Most of the info I find shows people running staggered setups with 20’s in the back and 19’s in the front. I’d much rather buy all 4 of the same rims and tires than do staggered. Do I need different offset for front and back? Different size spacers if I can’t find the exact offset, etc...? Any help is appreciated so I can find and add some rims to my parts list!!

 

Find out the size of the 19 inch tire and rim they used, and then plus size that setup. You should be able to copy the rim offset of the 19, and the overall diameter of the tire and rim on he 19 setup, and then substitute a 20 inch rim with a smaller tire.

 

thanks for that tip.
So I think I figured something out. They sell the old lightning rims for these trucks online and the only option for those are 20x9 +8 and 5x5.5. So I’m thinking as long as I get 20x9 and make sure my backspacing/offset is close to that same +8 I should be fine....

 

If you get wheels with the same width, offset and backspacing you just need to make sure the tires aren't any bigger than the outside diameter than the ones you have now. Make sure the wheels you get have a large enough center bore diameter and the spinner is deep enough to accommodate your hubs.

https://tiresize.com/comparison/

 

so that’s the problem I’m having right now. The bore on the rims that I really want is smaller than the damn hub! When I look online at the hubs, it looks like the rotor has a lip that’s large and then it reduces some. I’m wondering if spacers would get me above that larger part on the rotor. I see people also bore out hubs on the rims... I’m just torn. I really want these particular rims and it sucks that they don’t just FIT! Lol

 

I wouldn't run wheel spacers. Here's a thread with different opinions:

https://www.ford-trucks.com/forums/1...l-spacers.html

 

I know, I’ve been researching it. The spacers I’m thinking of are only 10mm tho and are just a plate that goes between the rim and rotor. Not the ones that bolt on and have other bolts to bolt the rims. I’m no expert, but I wouldn’t think only 10mm would stress things too much.

 

You would have to get longer wheel studs. Don't forget that if you overbore the center of the wheels you have then the spinners won't fit.

 

excuse my ignorance. spinners?

 

What we do on the old mustangs is put the hub in a lathe and turn it down. The late 70's granada disc brake spindle assembly as well as the complete rearend will bolt into a older mustang. But the original mustang rims have a small hole in the middle, the same problem you have on your desired rims. What people do is take the hub apart and take it to a machine shop, and they just put it in the lathe and turn the outside down till it fits the older style rim hole. The rearend also has a register that sticks out to center the granada rims, it's too big also. They pull the axles out, take them to the machine shop, and they turn it down a little till the old style rim fits the rear also.

 

thank for this info!!! I was thinking along those lines also, but wasn’t sure of the possibilities there!

 

Spinners, center cap, hub cap, etc. It depends on the style of wheel you have. Sorry.

Pics would help.

 

ohhhh! Ok I know what you mean now. I noticed some have that really long hub that sticks out. I don’t think this truck has those. The truck is actually still at my grandmas and is currently out of commission. Just getting all of my parts list and game plan together right now before I start to restore it.

I inherited it a couple years from my grandpa that passed and the truck is just sitting there going to ****, so it’s about time I start getting on it before it gets too far gone!

Trying to research and learn everything I can in the mean time before I bring it home and get after it! Lol

 

10MM / 3/8" is not a big deal and I have a pair of 3/8" on my 70 AMC Javelin.
The wheels Tq Thrust (TT) wheel would hit the factory dual piston calipers and spacing them out just a little was all it took.

As for the "longer lug studs" depending on the wheel & nuts used you may not need to.
The Javelin wheels use a lug with a shank the spacer has holes large enough for the shank to go through and is used to center the spacer.
So what was needed was to measure what the wheel needed for a shank on the lug and then add the spacer to it.
This way the longer shank lug goes through the wheel, with a washer, and through the spacer, yes a PITA to get lined up.
I just had to make sure the shank was not too long and bottom out before the wheels were tight.

I swapped out the dual piston for later normal calipers, could not get calipers or pads for the dual set up.
With the new disc I did not need the spacers up front so I moved them to the rear with the longer shank lugs.

Think this was also an issue with AMC cars from what I remember and some wheels not fitting the hub.
It may have been a bigger issue on the rears as the AMC axles & hubs were 2 piece and used a nut to hold them together.
This nut assy. stuck out pretty far so some wheels could not be used with a center cap and maybe the hub hole might have been too small too.

I have a set of 5x4.5 wheels that don't fit the 5x4.5 hubs on the rotors, don't remember about the rear will have to check but turning the rotor hubs may be an option if I want to use the suspension & wheels?
Dave ----