Moving from 265's to 295/70 or 315/70 KM3 in the next few weeks (both are in my garage for test fitting). I currently run Icon UCA's and trying to figure out if it's worth the trouble of switching to SPC's.

How much tubbing of the firewall would SPC uppers save me over traditional UCA's if I decide to go with the 315's??? Is it worth the hassle of switching?

Not worth it since you've already got icons. The geometry doesn't change much between the aftermarket Ucas and stock ones really, you just gain correction for caster, and the arc of the up travel changes very slightly at the wheel.

If your main concern is fitting the tires while trimming as little as possible, make sure your wheel fitment is as dialed as you can get it. Aftermarket UCA's have more clearance to the sidewall of the tire and let you run higher offset wheels. With my Total Chaos UCA's I can clear a 35 fairly easily on a 17x9 with 4.5" backspace. I'm fairly certain 17x8.5 4.5" would clear as well. Keeping the wheels as close to the UCA as possible shrinks the scrub radius and pulls the tire surprisingly far from the firewall when paired with max caster, compared with running 3.5" or even 4" backspace.

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@UnderFire Thanks! ....so just have the alignment guys put in max caster? That won't wear the tire unevenly?

At a 3" static lift height max caster has always put me within spec for camber, no tire wear issues and drives like factory with aftermarket UCA's. It's tough, but possible to pull a lot of caster with stock UCA's too, but has the side effect of causing the steering wheel to return to center much harder than normal.

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They could save you some cutting because you can set the lowers as far forward as possible and correct alignment at the upper. BUT you need an alignment tech willing to put that time in to get it right.

You will probably still have to cut a lot though.

Ok, this is what I was talking about. Yeah, I know I'm gonna have to cut, no worries there, I just wanna minimize it, so I don't have some huge hump under my feet.

Any idea how much more it pushed forward compared to my Icons and other normal aftermarket UCA's?

Good info and finding an alignment tech that's willing to dial everything in is crucial.

Op, not encouraging a body lift but without one you'll definitely have to cut a good bit. @TonyB66 took some pics of what it should roughly look like with your lowers set as far forward as possible. Just keep in mind that once the alignment tech (assuming it's a good one) dials everything in, the LCA settings might change a little bit (it did for me slightly).

SPC UCA Alignment Sheets
Thread #164

Most guys that tub do so to fit 35's. Decide if you want 295's or 35's before you tub. You should be able to get away with just the pinch weld mod with the Icons on 295's. Your wheel offset will also play a factor. Just take out the front coilovers and put on a test tire. Cycle the suspension and you'll quickly see what needs to happen.

As far as SPC vs Icon's go if buying new I'd say get the SPC's. Since you already have the Icons I'd just test fit with those. The SPC's will move your tire forward but you will sacrifice caster to do that. On the G setting, which is equal to 0 added caster, they will move you forward about 3/4".

@fourfive & @theesotericone

Thanks guys! I'll keep the Icon UCA's then and make it work.... def not doing a BL.

Are UCA's mandatory for a 315? I'm running FN 5-stars 16x8 -25mm offset.

I'm trying to avoid a body lift too and may end up with a 295, still trying to make that decision.

Thanks for all the info!

UCAs definitely aren't mandatory but with 16x8 -25mm offset 3.5 bs wheels on 285s or larger tires you'll definitely have to do some pinch weld & firewall hammering and trim the fender liner & flares if you have them.

I'd have to caveat what @fourfive said.... you may not need UCA's for clearance of the tire's sidewall, however, generally people max out (or close to) their front coil-overs to get the lift for 315. This is going to put your stock UCA bushing at a very extreme angle, and cause it to fail very quickly.

Aftermarket UCA's typically change the tracking of the front suspension, even is only slightly, but their biggest benefit when lifting so high is that they don't use a very basic bushing to pivot. Most use a uniball, but SPC uses something els, not sure what it is haha. So really, if you wanna run that large of tires, even 295's, you might wanna think about UCAs.

For your info, here are the tires I test fit last night statically. They're all fully aired up:

315/70/17 KM3 - FN 5-Star 17x8.5
295/70/17 KM3 - FN 5-Star 17x8.5
265/70/17 KM3 - Tundra Split Wheels 17x7.5 (20k miles old)

Just run the 315s. You know you want too. Or you could go full retard like I did and get PitBull Rockers in 35x12.5x17. They are 35.25" at the shoulder so at least 3/4" bigger then 315s. Making those things fit and not rub without a body lift was a b!tch. lol

Those 3.5" bs wheels are gonna hurt ya, better get the Sawzall warmed up...

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FN 17's are ET -6 or 4.5" bs. At most, I'd add a 0.5" spacer, which would be 4" bs. Def not gonna be running 3.5" bs.