Almost spun out on the freeway after alignment.
 

so I had recently got new tires in the back 245 40 18. & in the front I have 245 35 18.
I raised the back due to excessive rubbing.
My fender was carving my tires side wall all around on both tires in the back. So after I raised it I drove and it would swerve at high speeds. I figure I need an alignment !
So I go to a pretty well know tire shop
(BEST TIRE SHOP OF FONTANA)
After doing so it felt centered on the streets hands off the wheel test and all.
I get on the freeway way I do a pull to see if the alignment fixed my “swaying” issue
I’m at about 90 on a verrry gradual curve
Any car could make this “turn”.
Once I pass this turn my car begins to sway again I tried to re-center while letting off the gas but it felt like it wasn’t responding to the steering. Eventually the car went sideways right to left 2 times before I pulled the
E-brake and regained control.
Which left me wondering if not my alignment
What is the source of my steering issue ?
My tire setup?
Thanks for reading and excuse my ignorance.


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punching those sizes into a search engine yields rolling diameter of 26" in the rear and 24.8" in the front.


did the dash light up?

And is that where the issue is ? Again excuse my ignorance!
And my tracation control was off but no CEL.
My tire pressure light has always been on due to aftermarket wheels. Everything was back to normal


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Pulling the e-brake to "regain control"?! FFS, don't do that.

Car begins to sway and you lift off the gas = BAD move. Lift-throttle oversteer. Further exacerbated by pulling the parking brake. Jeezus...

Why did you get rear tires 1" taller than stock and front tires? I think you'd be better off with 245/35-18 all around but honestly I think it's the least of your issues...

Would be good to know your alignment settings as well but primarily get some learnin on basic car control.

I was already sideways for the 4th time till I pulled the ebrake. It wasn’t until I did so that I regained control of my car and left without a scratch thank you for the second half of your response tho [emoji1419]


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And is that where the issue is ? Again excuse my ignorance!
And my tracation control was off but no CEL.
My tire pressure light has always been on due to aftermarket wheels. Everything was back to normal


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I was already sideways for the 4th time till I pulled the ebrake. It wasn’t until I did so that I regained control of my car and left without a scratch thank you for the second half of your response tho


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Why are you running different aspect ratios front to back?

Post the alignment printout, we need more info.

Because I decided to run different tires in the back which came in different sizes none including the sizes I have in the front so I went with the 245 40 18 not realizing the effect it would have on my car. And the tire shop didn’t give me any details just gave me the car and that was all.


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These tires were brand new? If they were, they have to be worn in first for a few hundred miles or so. The mold release oil/gel that they use during the manufacturing process make them very slick.

Ok. Here's some advice on this for yours and everyone else's safety.

1. DO NOT run different tire compounds/treads front and back and expect to be safe at any speed greater than 10 below the speed limit for a given road.
2. DO NOT turn off traction control if you are at all unsure about your ability to keep the car in line (whether due to ducked up suspension or any other cause), especially if you are not following item 1.
3. DO NOT run different diameter tires on cars that aren't designed for them from the start.
4. If any of the above seem like a solution to a problem, find a different solution.


Now that we are through the don't-dos, here are some things you should do.

5. Do some research on "Traction Control", "Vehicle Stability Control", "Automatic Braking System", and "Electronic Brake Force Distribution". When you can explain to someone how they all work in detail, that is when you will understand your mistakes.
6. Do some research on tires concerning their construction and variety. When you can explain to someone what makes one tire different than another in detail, you will be able to make informed decisions regarding what tires to put on your car and how that may affect it's dynamics.
7. Do some research on suspension geometry. It sounds like you may have some seriously compromised aftermarket suspension setup if you are rubbing the sidewalls of tires.

Thank you !


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If you lease a car, run over-sized tires all around so you can get extra miles on the lease. For the Spark, I needed wheel spacers and spring helpers in the front, and had to swap the different offset front and back wheels to do it. In the end, I got a better ride, better handling, and 1500 miles of extra range. Oh, and a higher top speed.

New tires have poor traction in my experience.. Drive them for a bit and you should be fine..

How did locking up the rear brakes help you regain control? You entered a corner at 90+ and then made yourself lift causing oversteer.... where was the "curse" in all this!!?? Can you post some pics of your car and setup?

90mph turn on public roads and any car take this turn? I might be wrong, but aren't speed limits in US lower then that?
Traction Control off - better don't do that on public roads. During daily driving/cruising attention level is way way lower then concentration on track, and there can be many uncontrollable & unpredictable variables. Suggest to keep at least vsc sport as minimum.
If you change car rake, it will change also grip balance more to oversteer
If you needed to change tire size to reduce rubbing, imho that sounds like your car has many handling issues from chosen tire/wheel sizing and overlowering. Some unwise mods in that area need extra mods to fix introduced issues, or reduce extent of mods/changes that made car worse.
If you select tire sizing way off from stock, then it's always worth to do in more educated fashion to know what one is doing, then going by hunch of what "subjectively seemingly looks cooler" and possibly introduce handling issues.
How high you may value mentioned alignment shop says nothing to us. Post actual alignment values to see for abnormalities in those. The reason why it's always worth to ask for alignment printout - to ensure QA of their work and for others to enable to give actual useful advises instead of playing spanish inquisition and guesswork games.
If car is oversteering, driving inputs that add even more transfer mass & grip to front, reducting those from rear, will make it even worse, so one shouldn't brake or lift-off mid turn, just judge reasonable entry speed and balance neutral grip with partial throttle mid turn. Or rely on nannies, that you have turned off due overconfidence.

In my eyes result was caused by several factors, them all enhancing each other issues/impact to handling. As to which ones are better to fix .. not enough info in OP.

legal speed limits are much lower in most areas, set to 55 or 65mph.

however many roadways have a sort of unspoken 70-90mph running speed that moving at a slower pace actually creates more of a rolling roadway hazard.

not sure how you came to this theory when its most likely wheels that were not thought out if they would fit or not

I think there is a sticky by Racecomp on this subject already!

https://www.ft86club.com/forums/showthread.php?t=67345

You know, that's a good question... I don't really remember, but it made sense at the time. :iono:. Maybe I meant to include "suspension/wheel" in there or something.

Your back tires are too tall. It will make it so they read slower than the fronts. Therefore the car won’t know they’re losing traction until it’s too late. Fix the tire setup first, then get the alignment checked again and post the printout. We can’t really help more without more info.

It’s not a turn. Excuse me not knowing the exact term. But it wasn’t a straight away on the freeway. More like a curve that requires you turning the wheel slightly to the right.
Before I ran the 245 40 18 I could hit these roads at 90 with 100% confidence. But while on the new tire setup in the back the car felt like a boat rocking left to right. As if it wasn’t responding to me trying to keep it centered while in my lane.


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Yeah it totally was the tire setup. I went back to 245 35 18 and I passed this same spot on the freeway with no issues.
I didn’t realize the two tires in the back would change the dynamics of the car.


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This was exactly the issue ! Again excuse my ignorance. I didn’t know the height would effect the steering so much. Went back to the 245 35 18 all around and it feels how it should! I started this thread right after the incident so I failed to explain clearly. Especially the section of the freeway That the accident occurred


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Glad you figured it out!

I failed to explain the scenario [emoji24][emoji24]
It wasn’t a corner ! Mannn it’s one of the sections on the freeway it’s not a turn but a sliiiiight curve you’d see on a freeway


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Tire compound difference + larger rake angle from larger diameter rear tires (further reducing traction at rear)... keep same exact tire and size on all four corners from now on.

I experimented with track performance tires front and stock tires rear and it was hilarious fun in slow speed corners/in town traffic...not so much fun at highway speeds or high speed turns.