Need some help picking tire sizes for a 4/6 drop
 

I'm thinking about buying some wheels and tires for my build today for my 87' C10. Going with Torq Thrust II's. Pretty sure I am going to go with 20's (wanted 18's but tire sizes for that wheel are really limited). On the Front I was thinking either: 1) 245/45/20, or 2) 255/45/20s (20x8 wheel). The rears I want to use 295/40/20s (20x10 wheel).

I'm pretty certain the rears will work with no issues. After reading a lot here I am somewhat concerned about the fronts. I'd like to retain the stock inner fenders with my build and my concern is about rubbing issues.

Drop up front is a western chassis 2.5" drop spindle and one coil cut off the springs - would estimate this at about a 4.5" drop.

The 245/45/20 wheels spec out to around 28.7" tall
the 255/45/20 wheels are about 29.1" tall

I would much prefer to go with the 255/45/20 wheels up front, but again - not sure this will even work. The backspacing for the front wheels will be 4.50 in.

Any input is appreciated - the web is running some sales on tires today so was hoping to wrap this up. If anyone has a suggestion of a different front size please let me know.

Re: Need some help picking tire sizes for a 4/6 drop
 

Based on my limited experience, it looks like that'd fit - my truck had 265/75/15's (basically 31x10.5) on 15x8 rallys (4" backspacing I believe...) on it, with 2.5" drop springs and sagging stock 6cyl springs up front (with a 350 installed.) I had no rubbing at all even when I bottomed out the front suspension over dips in the road or doing hard off camber full lock turns into a steep driveway.

I'm in the same boat as you, but trying to run a 17x9 with a 255/60/17 up front on a 4.5-5" lowered truck, and haven't figured out what backspacing I need or if I should go with a 17x8 wheel instead.

Re: Need some help picking tire sizes for a 4/6 drop
 

The 245/45/20's should work fine. Mine was lower in the front and I ran a 245/45/18 which granted is a 26.7" but I was also at a full 6" drop in the front.


Rear was the 295/40/20 which fits perfect with the 5.5 BS.

Re: Need some help picking tire sizes for a 4/6 drop
 

Well I ended up going a completely different direction. Ended up ordering some 18" wheels and 235/60/18 for the fronts on a 18x8, and a 265/60/18 on the rear on 18x9 wheels. I like the look of the 20s but I wanted some more sidewall as I plan to drive the heck out of this thing and our Iowa roads are not the smoothest.

Re: Need some help picking tire sizes for a 4/6 drop
 

Please post some pictures..I'm leaning towards 18's as well. Connecticut roads are pretty rough too. I am currently running 29.1" tall tires now.

Re: Need some help picking tire sizes for a 4/6 drop
 

I'm also interested in seeing some photos. Those aren't too far off from what I'm going with for pretty much the same reasons. I want to be able to beat the snot out of my truck including washboard dirt roads and even our paved roads aren't awesome in Maine.

Re: Need some help picking tire sizes for a 4/6 drop
 

This is my '81 . "4/6" drop - flipped rear and belltech 3" drop spindles with one coil cut on stock springs.
The 18" wheels and 255/55R18 tires came with the truck, Don't look too bad but the front does rub quite a bit. It hit the part of the inner fender where its lowest and bolts to the outer fender. I think these tires are about 29" tall.

Re: Need some help picking tire sizes for a 4/6 drop
 

That looks great. I plan on running a 255 section 29" tall tire in the front so good to know where I might need to massage or make some room. Do you know what back spacing those wheels are?

Re: Need some help picking tire sizes for a 4/6 drop
 

The wheels are 18x8.5 with "0" offset. About 4.75" backspacing. I didn't see how I could easily make more clearance due to the lip where the inner fender meets the outer, So I actually have some 255/45R18 tires (about 27" tall) I am going to swap on.
Theres not a lot of choice for "truck" size tires in the 18" wheel size, as you may have found, But Hankook has some sizes.

Re: Need some help picking tire sizes for a 4/6 drop
 

I'll be running 17s but I've definitely found that same thing. Hard to find matching 275/60/17 and 255/60/17. I'm doing 17x8 with 4.5 back spacing in the front. I guess I'll see where I land and adjust as needed. Your photos are the closest I've found on a square body (and it looks great BTW)

Re: Need some help picking tire sizes for a 4/6 drop
 

I'm also running 1.5" spacers on the rear which really made a diff in looks.

Re: Need some help picking tire sizes for a 4/6 drop
 

I'll be running 17x9s with 4.25" back spacing and figured I'd have to use spacers to adjust to get the look I'm going for

Re: Need some help picking tire sizes for a 4/6 drop
 

Ridler 645 in Chrome 18x8 up front & 18x9.5 in the rear.
Tires are Pirelli's 265/65/18 all around.
PO had 20's on there, but I really like the 18's much better. I noticed that it rides much smoother than the 20's.

Re: Need some help picking tire sizes for a 4/6 drop
 

what brand of spacer did you use , thanks

Re: Need some help picking tire sizes for a 4/6 drop
 

It looks like you're around a 2/4 drop? Do the fronts rub at all? What is the offset or backspacing on the rims?

Great looking truck!

Re: Need some help picking tire sizes for a 4/6 drop
 

Rocket "Attack" Wheels
Front 18x9 4.5 inches bs-275/35/18
Rear 18x10 5 inches bs-275/35/18

Re: Need some help picking tire sizes for a 4/6 drop
 

Never have been sure on the drop. My brother believes it's a 2/4 drop. There is no rubbing at all. 2" backspacing.
Here is a before pic of the 20" wheels. I really did not like these wheels or how it rode. Every little bump in the road was felt. Big bump felt like the truck was coming apart.
20x8 with 255/45/20
20x10 with 285/50/20

Re: Need some help picking tire sizes for a 4/6 drop
 

heres a couple of 18" equipped squares that I found on here. 295/45/18 on rear and 245/45/18 on front of white one and 255/45/18 on front of blue one. hope pics post!

Re: Need some help picking tire sizes for a 4/6 drop
 

That white one is perfect. I have 15s and want a bigger wheel but not loose on side wall. 295/45/18 is what I want to run in the rear with 245/55/18 on the front . I like a leveled truck and nice side walls.