People with 285’s and no CMC

If a CMC is needed I’m ok with getting it done and I’m thinking of 17x8.5 with 0 offset

 

Stock 2021 trd pro with wescott lift and no cmc, wheeled a few times and no rub.

 

285/75/16

 

No choppy choppy here.

 

So a more negative offset means higher chances of needing cmc?

I want 285/70r17 with 17x8.5 -10 offset on a 2/1 lift. Will UCA's help me avoid CMC? Otherwise I could go with my second option wheels 17x8.5 with 0 offset. I thought a more negative offset means LESS chance of rubbing the stock UCA's.

 

More negative offset = less chance of rubbing UCA but higher chance of rubbing cab mounts.
I have 16x8 0 offset with SPC UCA's, 3in lift and do not rub my cab mounts but am close at full lock and flex.

 

So would getting adjustable UCA's help with cab mount rubbing? I need to decide if $600+ is worth it going with -10 offset instead of 0

 

New UCA's would help by moving caster as far forward to get away from the cab mounts.
My SPC UCA's helped me clear the tires from touching the UCA and my cab mounts.

ymmv since every truck is a bit different but this was what worked for me.

 

@Raijin822 is incorrect. When you add UCA's, you gain caster. Positive caster that is. That is done so by moving the UCA closer to the cab. The only way to gain positive caster and move the wheels more forward would be to replace the LCAs.

Now it is possible to fine tune with an adjustable UCA. You would start by maxing out the LCA adjusters then dialing in as much caster as you can with your UCAs, but you still won't gain anything, just a way of not losing as much. This picture explains caster and should help clear up what is going on when you replace your UCAs to gain caster -



With very few exceptions, no car made in the last 50 years has negative caster. You ideally want somewhere around +3 degrees of positive caster.

 

You are correct. My poor wording.
Max out my LCA and have SPC correct the alignment which helped me clear.

https://youtu.be/f2YhnldfI50

Like this video at the 1min 45sec mark


Edit: if you max out the LCA, you won't be able to correct for proper alignment with stock UCA's.

 

Thanks, so im assuming the stock LCA has some adjustability? I'll probably install the wheels/tires and then decide what needs to be done. Im hoping the tire shop knows what theyre doing and can make the right recommendation.

 

Just had a CMC done today (Adventure Fab, Vancouver, WA). I was rubbing in reverse only - maybe just plastics but decided to gain the clearance.

RC 3.5” front/2.5” rear block/RC UCA’s
17x8.5 0 offset 285/70/17

close-up shot is at full lock

 

I’m on 285/70, no CMC, no rubbing at all. 2.25” lift in the front with SPC Uppers pulling like 2.9 degrees of caster. Wheel spec are 17x8.5 -10mm

 

The stock LCA is where you adjust camber and caster. The stock UCA has no adjustments.

There is a very, very fine line between rubbing and not rubbing. If you are lucky enough to find a shop that has someone that cares, it can be done. Problem is that most techs just want to set the toe and be done with it.

I would mount your wheels/tires first and see where you are at. I mistakenly ordered a set up CMC plates when I got my new wheels and tires fully expecting to have it hit the mount based off what I read in this thread. I'm Running 285s on stealth -10 17's, but I didn't come close to the mount. Luckily I didn't spend the time cutting the mounts. I did rub on the plastics. When I took it in for the alignment I had them max out the caster which with 2" of lift was able to get 2.3 degrees. It drives ok. I would like to have more caster, but not worth the hassle and cost with this set up.

 

yeah that’s probably what I’ll do, it seems like a crap shoot either way. Some people rub and others don’t on the same specs. I’ll need to find a good alignment shop.

 

5100 Billies, 3rd setting, 285/70r17 Falken mud tires on 4Runner SR5 wheels I got from a bud for $200, some mild heat gun work on fender liners, thinner (rubber) mudflaps, and it's all good. Kept my "first upgrade" all-season 265 Wranglers on the stock 16 inch OR wheels as my winter tires.

 

I have 285/70r/17s, Zero rubbing and no CMC. I am pretty sure I am at zero offset but would have to double check.