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Old 11-26-2018, 10:23 AM   #1
Mattchu60
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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.

Last edited by Mattchu60; 11-26-2018 at 10:54 AM.
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Old 11-27-2018, 11:17 AM   #2
skyphix
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Re: Need some help picking tire sizes for a 4/6 drop

Quote:
Originally Posted by Mattchu60 View Post
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.


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.
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Old 11-30-2018, 07:49 PM   #3
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Re: Need some help picking tire sizes for a 4/6 drop

Quote:
Originally Posted by Mattchu60 View Post
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.

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.
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Old 11-30-2018, 09:51 PM   #4
Mattchu60
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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.
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Old 12-04-2018, 05:34 PM   #5
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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.
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Old 12-04-2018, 10:43 PM   #6
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Re: Need some help picking tire sizes for a 4/6 drop

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Originally Posted by Mattchu60 View Post
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.
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.
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Old 12-04-2018, 11:06 PM   #7
StorminNorman
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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.
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Old 12-04-2018, 11:15 PM   #8
skyphix
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Re: Need some help picking tire sizes for a 4/6 drop

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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.
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?
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Old 12-04-2018, 11:40 PM   #9
StorminNorman
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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.
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Old 12-04-2018, 11:43 PM   #10
skyphix
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Re: Need some help picking tire sizes for a 4/6 drop

Quote:
Originally Posted by StorminNorman View Post
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.
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)
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Old 12-04-2018, 11:45 PM   #11
StorminNorman
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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.
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Old 12-04-2018, 11:47 PM   #12
skyphix
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Re: Need some help picking tire sizes for a 4/6 drop

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I'm also running 1.5" spacers on the rear which really made a diff in looks.
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
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Old 12-05-2018, 06:43 AM   #13
TKCR
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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.
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Old 12-05-2018, 11:31 AM   #14
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Re: Need some help picking tire sizes for a 4/6 drop

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I'm also running 1.5" spacers on the rear which really made a diff in looks.
what brand of spacer did you use , thanks
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Old 12-05-2018, 03:54 PM   #15
skyphix
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Re: Need some help picking tire sizes for a 4/6 drop

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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.


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!
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Old 12-05-2018, 04:52 PM   #16
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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
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Old 12-05-2018, 06:51 PM   #17
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Re: Need some help picking tire sizes for a 4/6 drop

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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!
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
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Old 12-06-2018, 01:34 PM   #18
rustyfive-seven
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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!
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