Question about Drop and Wheel fitment

[bewsii]

Hey guys, I've been a lurker for years now but I guess this will be my first post, hah.

I have a 97 C1500 Ext. Cab 2WD with a 0 mile crate 5.7L Vortec. I am now at the stage where I am ready to purchase my drop kit and wheels, but after a ton of research I'm still unsure on the route I want to go mostly due to my lack of knowledge with wheel fitment. I've been in the custom car scene since the 90's (worked at performance shops doing engine swaps) so I know cars well, but unfortunately my experience with trucks is very limited.

This is more of a childhood dream build since my dad sold Chevy's in the 90's and I always drove his Demo's around. Now I get to build one 20 years later

I've narrowed my drop kit down to the McGaughys 4/6 with their add-on shocks. I was considering the DJM LCA kit first, but it seems like people prefer the spindle kits (despite wheel fitment issues that arise) over the LCA's since the LCA's are known for camber issues.

https://www.suspensionsuperstore.co...k-rotors-4-6-deluxe-drop-kit-mcgaughys-33138/

The two sets of wheels I've narrowed it down to (for now, at least) are these. Herein lies the fitment questions now that you have the information needed to know what will work best for me:

https://www.performanceplustire.com...ckage:so:prlow:vh:447764-1:yr:1997:ws:20x8-5/

20x8.5
Offset: 0 mm
Backspace: 4.75

https://www.performanceplustire.com...ckage:so:prlow:vh:447764-1:yr:1997:ws:20x8-5/

20x8.5
Offset: 10 mm
Backspace: 5.125


Everything I've read said with a 4/6 and 20x8.5's I'd want a 5" backspacing which seems to work better with the Vision having 5.125 vs. the Ridler's 4.75. But my confusion comes in where they also list the offset and how that effects my choice.

Does anyone have suggestions? I'm open to other wheels too. I'd like to go 20's with a nice lip for some depth, and keep the price under $2000 shipped with tires, if you know of any offhand.

Thanks!

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[brianmcb]

Offset is measured from the centerline of the wheel to the wheel mount surface. Backspace is measured from the mount surface to the very back edge of the rim.
So as backspace changes, so will offset.

Id aim for the 5.25" ish backspace on a 20x8.5.

The 4.75 may give you trouble with tire/fender clearance

95 rcsb, L33 5.3, hot cam, frost tune, 5spd, 4/6

 

[sewlow]

My 20's are 8.5" & 10". 255/45's & 295/40's. Toyo Proxes II. Decent tire. Pretty good tread life. Kinda hard, though. The added weight of the T's&W's, (About 22lb.'s per corner) along with the hard compound causes the front end to push somewhat in the corners. Being directional with the staggered sizes means no rotation is possible. So, I wore the outside edges of the front tires before the rest of the tread.
No clue on the backspacing, but 5" seems to be the way to go, judging from what I've read on here.
$1800.00 CDN. Just under $1500.00 U.S. For the tires & the wheels. Shipped across the country & a border to my doorstep in 8 days. Local tire shops wanted near 2x as much with anywhere from 4-10 weeks for delivery. The price included mounting & balancing, the shipping, border taxes & duties, & the eco-fees.
SDWheels. A.K.A Steve's Discount Wheels. Told him what I had, what was done to it & what I wanted. He handled the rest.

 

[bewsii]

Offset is measured from the centerline of the wheel to the wheel mount surface. Backspace is measured from the mount surface to the very back edge of the rim.
So as backspace changes, so will offset.

Id aim for the 5.25" ish backspace on a 20x8.5.

The 4.75 may give you trouble with tire/fender clearance

So the Vision wheels with 5.125" backspace should work in my case? The 10mm offset is the part I don't understand in regards to how it effects the fitment.

 

[brianmcb]

So the Vision wheels with 5.125" backspace should work in my case? The 10mm offset is the part I don't understand in regards to how it effects the fitment.

I would say yes they will work best of those two wheels.


95 rcsb, L33 5.3, hot cam, frost tune, 5spd, 4/6

 

[bewsii]

Thanks for the help. Do you think a 255/50 on 20x8.5 will be okay with the 4/6 drop?

 

[brianmcb]

Thanks for the help. Do you think a 255/50 on 20x8.5 will be okay with the 4/6 drop?

Seems like a tall tire to me. 40 series might be a better fit.
Maybe someone else can confirm.

95 rcsb, L33 5.3, hot cam, frost tune, 5spd, 4/6

 

[sewlow]

That's a pretty tall tire. Taller than the original stock size of 235/75-15.
You'd be better off with a 255/45-20. Longer footprint by 1/2". About a 1/4" taller than the original size. Only 4 revs per mile less than factory. Won't affect the speedo hardly at all. At 60mph you'll be doing in the neighborhood of 63.

http://www.1010tires.com/Tools/Tire-Size-Calculator/235-75R15/255-50R20/255-45R20?ismetric=False

 

[bewsii]

Yeah, I was actually looking at the 255/45's since they don't seem to offer 255/40R20's in the Eagle Sports. Seems like it'll have enough meat on it to not be too rough on bumps.

 

[bewsii]

Ok, after talking to a Tech guy at McGaughys, I went ahead and ordered their 4/6 Spindle kit (33137) and Shock kit (2x 1451 and 2x 2050). I used Summit and had them pricematch Grunion Customs price of $742 shipped for everything. McGaughys recommended Grunions, but I've ordered a lot of stuff (including my crate engine) from Summit and value their customer service.

Still need to grab a shock extender kit and make a decision on what wheels/tires I want. Currently still leaning towards the Vision Torque 143's, but I have to be sure it's what I want first. I'm sure you've all pained over wheel choices too