Help me out of this rabbit hole ! Lowering, wheels, backspacing, tire sizing - help !

[pnut16611]

I know this topic is probably beat to death here, but for a newb reading thread after thread, my search for answers only leads to more questions and I`m just chasing my tail here. `86 Sierra with 15x8 ralleys currently. My goal here is to lower it + wheels.
Shopping list: Maxtrac 3.5 / 5 kit (2.5" spindle / 1" spring).
Ridler 695s 20x8.5 with 245/45/20
20x10 with 275/40/20
Questions: 1) is kit ok ? No red flags everybody but me knows about ?
2) will my current ralleys work until I get the Ridlers, or no ?
3) Tire sizes suitable ? I`m trying to avoid any sort of rubbing altogether if possible & preserve a good ride. Would an 18" wheel & a bit more rubber be better for those purposes ?
Much appreciation to all for the guidance - I`ve been reading & looking @ pics for a week & just when I think I have it figured out, another question pops up - you know how it is lol. Asked the wheel / tire vendor question #3 & was told none of this matters, but I at least know better than that.

 

[Soundmound]

Start here.
Thread 'Wanna slam that 63-98 C10/C1500? Lets talk about it!' https://www.gmsquarebody.com/threads/wanna-slam-that-63-98-c10-c1500-lets-talk-about-it.38131/

 

[fast 99]

I worked at a tire store. Both of our counter people could tell you exactly what wheel, tire, backspacing and how much lift is needed from memory. What would fit and what wouldn't. Is there a tire store nearby that might help?

 

[pnut16611]

I worked at a tire store. Both of our counter people could tell you exactly what wheel, tire, backspacing and how much lift is needed from memory. What would fit and what wouldn't. Is there a tire store nearby that might help?

The wheel vendor has the wheel / tire package as listed above, with other tire options available. I asked would this be the optimal tire sizing for my application & he says yes. Just trying to verify.

 

[Scott91370]

Rubbing: Rear you will be 100% fine. Fronts you shuld be ok as well since you're wheel/tires will be inboard more than mine are. You're setup is a total of 2" taller than mine so it'll sit 1" higher into the fender, but without the spacers pushing them out you shouldn't rub.

More than likely id you have 15" wheels and you use a 2.5" spindle you will have interference - especially if you have clamp on weights. Once you up to a 20" or have better backspace/offset (like 1/4" more space between wheel and spindle) you'll be fine.
My setup is:
Front: 18x8 with 245/45 and a 1.5" wheel spacer. 2.5" spindle, 2" spring

Rear:18x9.5 275/40 and a 2" wheel spacer. Axle flip kit

Wheel spacers are made by BORA @ https://www.motorsport-tech.com/bora.html
Brings the wheel/tire combo out near the edge of the fender.

You must be registered for see images attach

 

[TotalyHucked]

I have never used MaxTrac, I always use McGaughys or Belltech because they are the top 2 quality companies and I've had great luck with them. No matter what kit you go with, run Belltech SP shocks. These are the best riding drop shocks on the market short of expensive adjustables. As a side note, you'll likely want to go lower. 3.5/5 isn't much of a drop on these trucks, so browse that thread @Soundmound linked to see what look you like.

Ridler 695s 20x8.5 with 245/45/20 - You should be fine with these, may rub on the inner fenders a touch. If you end up going lower up front, you'll want either a 245/40 or a 255/40 instead to keep rubbing to a minimum.

20x10 with 275/40/20 - You need more tire than that on a x10 IMO, a 275 on a x10 looks too stretched. I run a 315/35/20 on my 20x10.5s, I'd run at least a 295/40 if not a 305/35 on a x10.

Questions: 1) is kit ok ? No red flags everybody but me knows about ? - See above

2) will my current ralleys work until I get the Ridlers, or no? - They will but you'll end up rubbing the inside of the wheel on the front edge of the control arms at full lock. Not really an issue, either grind down the small lip that it rubs on or just don't go full lock.

3) Tire sizes suitable ? I`m trying to avoid any sort of rubbing altogether if possible & preserve a good ride. Would an 18" wheel & a bit more rubber be better for those purposes ?
Much appreciation to all for the guidance - I`ve been reading & looking @ pics for a week & just when I think I have it figured out, another question pops up - you know how it is lol. Asked the wheel / tire vendor question #3 & was told none of this matters, but I at least know better than that.


For reference, here's 3 different phases of my truck. First is McGaughy's 2.5" spindles and OE 3/4 ton big block springs with 1 coil cut (1 coil equals 2" of drop) and a flip kit in the rear. So I was at 4.5/6. 245/45/20s and 275/40/20s on 20x8 and 20x10s. Then same setup on 15x8 rallies and 235/75/15s (OE size) tires.

You must be registered for see images attach

You must be registered for see images attach

Once I put the LS in it, the front end rose up cuz an aluminum LS is much lighter than an iron small block. So I swapped my OE half ton springs back in and kept trimming them 1/4 coil at a time until I was happy. I ended up somewhere around 5-5.5" up front. A little side note, I don't like any of the aftermarket drop springs, they're all too soft. I would save your money and just cut your originals.

So this is ~5-5.5" up front and still the 6" flip kit in the back. The back was always wayyyy too high, so I rode around with ~400lbs of crap in my toolbox to bring it down. I've got Belltech's drop shocks up front and OE length shocks in the rear with shock relocators on the bottom. These are 20x8 with a 255/40/20 and a 20x10.5 with a 315/35/20.

You must be registered for see images attach

You must be registered for see images attach

So now the current setup is the 2.5" McGaughy's spindles, OE 1/2 ton springs trimmed till I was happy, 6" flip kit and a 2" shackle added in the back. I had to swap the rear shocks out for some drop shocks at this point but no other changes were made

You must be registered for see images attach