I have been having a heck of a time getting decent alignments on my runner. Toyota dealership will only do oem specs and not 4* caster. I called firestone and asked if they'll do an alignment for 33" tires and the tech said yes then checked with his manager who said no they can't do tires that big...even though stock diesel trucks come with essentially 35s now??? The manager then proceded to tell me to go to a shop that specializes in alignments for tractor trailers/ dump trucks
What gives? Should I just show up at firestone and tell them to align me? I'd really like to be able to drive without my fighting my steering wheel to stay straight

Just find a local alignment shop, preferably with older age techs. I would stay away from chain locations like Firestones, Meineke, etc...

Confused why you asked about doing alignment with 33's. like you said its not that big of a tire. I'm sure tech ended up asking if they do 38's or something. Go to a shop ask if you can get specific specs that you want. If they say no, go to another. My firestone tech lets me sit under the car with him and discuss everything together. Gives me exactly what specs I want. Just gotta find the right place.

I have the lifetime alignment on my 3rd gen and I've never had a problem at Firestone, my rig is pretty heavily modified too.

Most of these service managers when it comes to alignment on a modified rig, are full of corporate standard answers like car dealers. There are a lot of good techs out there but they are hard to find. I got lucky. I followed this guy with various vehicles for over 20 years from Tire Kingdom to, you guessed it, Firestone.
This 4th gen is a full Total Chaos front with UCAs and LCAs on 35s and my buddy Steve dials me right in every time. The manager will NOT do the lifetime because it has nothing left that's factory except the frame. Understandable if a lawyer ever has to get involved. Just good business practice. Basically most of these stores have no faith in their staff who probably aren't very experienced, and they have to deal with novice truck owners that complain about every little thing. But, short answer: Firestone does do good alignment, but only if you find the right store and technician.

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Tire size has nothing to do with alignment. So that’s a dumb answer. Things like a lift, adjustable arms, stuff like that yes. But tires don’t do anything