Any difference in alignment specs for different tire and wheel combos??

[RIBS]

Does anyone know if the alignment specs are different depending on your tire and wheel selection? My car came factory with 19 inch rims and I upgraded a year later to factory 20 inch rims and I’m wondering if I need to change the alignment because the inside of the tires wore more quickly then the rest of the tire up front I’ve also heard the 20 inch tire option from the factory also got you the cowl brace. I bought that and installed myself along with a shock tower brace.

Anyone have access to alignment specs? Thanks!

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[TheLion]

Does anyone know if the alignment specs are different depending on your tire and wheel selection? My car came factory with 19 inch rims and I upgraded a year later to factory 20 inch rims and I’m wondering if I need to change the alignment because the inside of the tires wore more quickly then the rest of the tire up front I’ve also heard the 20 inch tire option from the factory also got you the cowl brace. I bought that and installed myself along with a shock tower brace.

Anyone have access to alignment specs? Thanks!

As far as I am aware there is no difference in alignment between wheel / tire selection. Chamber up front isn't really adjustable, there's just enough slop in the holes that very small adjustment can be made to account mostly for production tolerance variations, but nothing like with a chamber plate. It's not intended to alter chamber other than to tweak it so it's within spec from car to car.

Caster is also fixed from the factory. In fact only toe in the front and rear is fully adjustable via cam bolts (rear) and tie rods (front), stock that is. What is the size of your 20" tires if you don't mind my asking? 275/35R20's?

I'm running 19x9.5's on all fours (RTR Tech 7 wheels). So I'm running 275's up front, widest factory tire up front is 255 on the 2015-2017 first gen S550's. I have a little more inside tire wear with the 275/40R19's than with the factory 235/50R18's, but nothing that affects long term tread life to any meaningful degree. Maybe at worst 1/64 or just a hair more.

Roll out on the 19's is 27.7 inches. Due to the added width your camber is going to be a little greater in the front as the tire is closer to the strut on the inside, which is where most of the width is added, otherwise you'd be rubbing fenders off if it were outward.

Maximum Motorsports makes some great chamber / caster plates for $250. They allow you adjust caster and chamber independently. There's also Steeda and BMR, all of which are great options quality wise if your out of spec. I would suggest just taking it in for an alignment to a known good shop or your local Ford dealer, find out where it's at first and if it's out of spec.

 

[NightmareMoon]

Nope, alignment specs won't change just from a wheel diameter change.... However...

When you replace tires, its probably time to refresh your alignment. Things drift over time, and it would be a shame to ruin a good set of fresh tires early because the alignment had gone a bit sour.

FWIW, the shorter 20" sidewalls may be slightly less forgiving of camber than a squishier 19" tire sidewall.

That said, camber is not usually the main factor in a tire that wears out early. Too much toe is usually the problem. Toe causes constant and relentless scrubbing against the direction of travel, and it can kill tires really early if its drifted too much since your last alignment.

 

[wildcatgoal]

I use the factory wheels without spacers when getting alignments to avoid variables. In theory there should be no difference, but I've done back to back sensor test with factory wheels vs. my 20" Project 6GR wheels (which were brand new, not bent, etc.) and the machine read differently. It shouldn't have, but it did. And if that machine did, others do... so I just roll in for my alignment with the factory wheels figuring that's my best bet for an accurate read.

 

[NightmareMoon]

well, the wider offsets on the P6Gr wheels are going to put more leverage on the suspension, so yeah it could torque things slightly but the OP's factory 19" -> factory 20" shouldnt do much.

 

[RIBS]

Thanks all for the input. Front tires size is whatever the stock 20’s are...too cold and wet to go look!!
My wear is pretty severe just on the inside edge. Like to the cords! The rest of the tire is 98% to the wear bars, but worn even. I wonder if that is not enough toe, the car is a little darty side to side going down the road. Or maybe low speed turning, like leaving garage??

 

[Rebellion]

There's a PDF around, can't find it right now...could only find this dandy chart, courtesy of BMR:
https://www.facebook.com/BMRMustangSupport/photos/pb.582867248483175.-2207520000.1458476825./598768600226373/?type=3

I the toe set for 0 on front and 0.1 on the back. If the car is too twitchy, you might have toe out, not a very common thing to have for a stock car.

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