Alignment after wheels/tires ?

i have a 2014 GT500 SVT/PP On stock SVT Suspension.

i posted in a previous thread in regard to lowering spring with my new wheels/tires.

I have installed HRE F001 20X9.5 20X10.5 with 285/35/20 305/35/20

my question on this post would is did my change in tire and rim size throw off my alignment/ride?

compared to my 16 GT/PP the shelby seemed to be a much more stable highspeed car. ie.. a 60-120 pull felt stable, smooth, and comfortable.

since the wheel/tire change, i have noticed the car seems to feel a little uneasy in the high speeds. i am not experiencing an unbalanced wheel shake, the car and steering just seems to be more "floaty"

do you guys think i have changed the alignment of the vehicle and this is why i am experiencing this?

i assume a "rougher" ride is due to the wider tires but the car doesnt have as much confidence as i previously felt.

I'm not sure I'm reading this as you changed to lowering spring or not. The changes of not changing the toe setting after lowering springs is pretty nil, unless it's sitting at the same ride height as before the change. Based on what you're describing, I'd say your toe is now out instead of slightly in which is what it should be doing. Unless you have adjustable struts, there's not a lot you can do with camber and caster adjustments. If the toe is off a lot, you could experience premature tire wear depending on how far from zero you are. But yes, get it aligned.

The rougher ride may be an increase in spring rates, but the shorter sidewall might add to it. I'd check my tire pressure. Sometimes tire shops inflate them to max to seat the beads and don't air them back down. Overinflated tires may also contribute to squirrelly handling.

If you didn't put lowering springs, depending on a change in wheel offset you could still encounter a slight change in ride height by moving the thread centerline (offset) inward or outward. So I'd still get it checked. I know these tires aren't cheaper than an alignment.

What tires are mounted on the HRE's?

I did not change suspension (currently on stock SVT suspension)

I had posted another thread in regards to possible changing the spring or suspension with my current tires size ( slightly larger than stock)


I am running BFG Gforce Comp 2 A/S

The rear offset is +45 not sure off hand on the fronts. I did do with a slightly taller 35 tire in the rear and obviously I went from 19” upfront to 20” upfront

just curious as to if I should make any changes/ adjustments.

Changing rims/tires isn't impacting your alignment. Any difference in handling and ride is due to the tire sizes, tread pattern, compound, etc.

Tom

You don’t think going to a taller ( 20” ) up front and a taller tire in the rear would through anything off? I have to check the offset of the front rims.

would anyone recommend maybe a different alignment spec? Even if I’m “in stock spec” for a better straight one pull and handling ?

If you lowered your car or did anything suspension related you should have your alignment checked and adjusted as necessary so you don't turn those brand new tires you installed into waste.

Driving on tires with improper toe or camber settings can chew up your tires in no time. You can get away with running up to -1 to -1.5' of Camber without wrecking your tires. The more - camber helps with cornering. A tiny bit of static toe in is perfect for street driving and if you track a lot then 0 toe or slight toe out will be better for handling on the racetrack.

Get adjustable camber plates so you can dial in your Camber and Caster settings when doing an alignment.

285 size tires on a 9.5" wide wheel is a tad big, that size tire should be on a 10" wheel, 10.5" is perfect but hard to fit on the front of a S197.

Tony

When I was 100% stock SVTPP suspension and installed new wheels and tires my handling and stability only got better. New wheel/tire setup was 20x10 285/35/20 and 20x11 315/35/20, larger diameter both front and rear and again handling and stability only got better.
Agree a 9.5" wheel is a little narrow for a 285 tire, a 265 or 275 is the widest I would go cause past that your probably getting some tire roll over under hard cornering.

Perhaps your alignment was is slightly off and the OEM goodyear tires didn't show this but the new stickier BFG's are making the mis-alignment more apparent. Past that though I'm wondering if it's the tires themselves are causing the instability. There was a lot of documented issues with either a certain MPSS or a batch of them causing a "death wobble" at a higher speeds.

You aren’t changing geometry with tire size. Nothing will change with a whee swap.

May be the tire.

Sidewalk rock.

I had a set of tires on my cobra
So bad
Car felt like it would roll over at 60 on a curve And like you. High speed was life or death.

merkyworks said:

When I was 100% stock SVTPP suspension and installed new wheels and tires my handling and stability only got better. New wheel/tire setup was 20x10 285/35/20 and 20x11 315/35/20, larger diameter both front and rear and again handling and stability only got better.
Agree a 9.5" wheel is a little narrow for a 285 tire, a 265 or 275 is the widest I would go cause past that your probably getting some tire roll over under hard cornering.

Perhaps your alignment was is slightly off and the OEM goodyear tires didn't show this but the new stickier BFG's are making the mis-alignment more apparent. Past that though I'm wondering if it's the tires themselves are causing the instability. There was a lot of documented issues with either a certain MPSS or a batch of them causing a "death wobble" at a higher speeds.

Click to expand...

May I ask what your offsets are?
This is exactly what I'm looking for.

front is 38
Rear is 58