Instability/wandering steering on freeway/highway speeds

I have the same problem with my 2017 that I have had for a year. Got use to it for now. Thought about getting the alignment checked but haven’t at this point in time.

 

more of a prius thing. try different tire pressure. might need alignment, should be free for 12 months.

ultimately, you might need different tires, certain road pavement can affect the oem's

 

Last June we took our 2017 Prime on two 500 mile road trips and had no problems, even at highway speeds. If your Prime is handling so poorly that you feel there's a crosswind, there's something wrong. The most likely problem is alignment, but it could be a suspension problem or a tire issue. Your new 2018 should be under warranty, so you should take it into your dealer to correct the problem.

New cars can suffer alignment problems or even damage because of the way they're handled getting on and off the car carriers used to transport them to the dealership.

 

Hmm can't say I've noticed it with mine. You DO feel a crosswind, for some reason more pronounced in the Prius than other cars I've had and the Prius isn't exactly the lightest car, I've driven lighter cars that didn't seem to get thrown around. But as far as wandering around in the lane, never really had an issue, stays pretty straight.

That being said, pavement can have some effects, especially in construction zones and whatnot but some of that is any car. So could be tires or an alignment issue. Might be differences between the Prime and what you used to drive. Coming from a Challenger to a Prius was a big change, Prius to Prius Prime not so much.

 

Look into a Brand called Cusco.

They make underbody braces that help with the stability of the car

We installed a package at the shop and the Owner was quite impressed!

 

Could be an alignment issue (even new cars). Having driven this car for extended periods over 85 MPH through central Cali, I can say that it's very stable, even in cross winds. I've noticed more "kick" when passing 18-wheelers in my Camry actually. The "kick" is that lateral push away from the 18-wheeler when you pass through the wake effect created by the huge frontal area of the truck.

 

My 2017 is very stable. Get a 4 wheel alignment done.

 

Likely something to do with tires. Different tires have a different feel.
I once had a set of Michelin Hydro-edge's on a Caddy that I HATED. Most people like them.

Some dealers will try to screw you .......since tires are not covered under the Toyota warranty but the tire company.
But it could be something else; something important that could eventually be dangerous so you should have it checked.

 

All I can say if it is the stock tires, Nano Energy, they drive just fine. Of course, that's not to say that someone couldn't have a defective tire... At any rate, only thing I can suggest is since it is so new go test drive another 2018 Prius, see if it behaves the same way. The Prime and regular Prius, feel pretty much the same on the road, if anything the Prime feels more solid on the road. They should drive pretty much the same. I drove my 2016 Prius up to Connecticut to trade it in for a Prime and drove it back to North Carolina...Both cars felt very similar on the highway, they have some differences but wondering and handling were not present on either car.

 

If the dealer did a wheel alignment before selling it to you. They probably missed the zero calibration part, or power steering calibration.

Or your power steering is simply not calibrated and needs to be calibrated again. This fix is quick, it should take less than 5 mins. All they have to do is connect their diagnostic computer to your OBD plug, and they will perform the calibration.

Try that, before you try other things like getting new tires, alignment, different tire pressures, etc.

Thats how my freeway swaying/wandering went away. Good luck

 

While this issue could be many of the already reported causes, I will tell you what I believe the root cause to be:

OE Tires & Wheels.

1) Tires: My Prime came with a Nano A29 which are "S" speed rated, S speed rated tire by themselves are sloppy feeling when compared to a higher speed rated tire. Also a "65" series tire (195/65-15) is geared much more towards softness/comfort, this greatly Aids the floating feeling at highway speeds.

2) Wheels: By upgrading to a 16, 17, or 18" you are forced to make the sidewall of the tire shorter in order to achieve the desired 25" overall diameter. A common 16" wheel makes you buy a 205/55-16 (Or a 17" with a 205/50-17, 215/45-17 or 225/45-17) tire to achieve the desired overall diameter, this reduction in sidewall height greatly improves how the tire reacts/feels on the road. Plus in almost all cases the speed rating now jumps up to an "H" or "V" speed rating which is firmer when compared to a "S" rated tire.

Let's sum things up:

If you stay with the stock OE 195/65-15 tire size, Upgrade to a "H" or "V" speed rated tire for better road handling feel. The higher speed rating will make your Prime feel "slightly" less like a Chevrolet Cadillac, but in turn will slightly firm it up so the "floaty" feeling gets diminished. If you also upgrade to a bigger wheel diameter, your new tire will have a shorter sidewall & a higher speed rating which when combined will Greatly aid handling & feel.


Rob43

 

Additional comments:
I see you are in California. Seems like I remember that they are prone to putting DEEP rain grooves in some or most of their roads.
That could be a BIG factor.

Also be sure that your tire pressures are at the recommended value.
Too low or way too high can be a problem, depending on the tread design.

And one wild idea: Were you driving with the windows down ? If so, try it again with them UP.

 

You'd be lucky if they checked the tire pressures, lol.

What would cause the highway wander, front toe-in off?

 

I had this Exact problem,.....and solved it. (Post #12)


Rob43

 

Would runflat tires, like bridgstone driveguard, fix the instability? I know all the hate for them, but I've had eaglef1 runflats on my vette for about 5 years and they no joke saved my life once. I'm just thinking because they'll be a little heavier (like 11oz a corner) and a lot firmer, without having to change rims. I've never messed with rims and looking into it, it seems more of a hassle and more expensive (like $1600 for rims and tires vs $600 for runflats). I really don't care about the looks, and don't care about the performance (other than fixing the stability at 80mph) just thinking what would be most cost effective and I generally hate lo-pro tires. My last car was a sonata with 16" rims and nice big marshmallow tires and it felt planted on the highway with none of this instability bs. The driveguards are supposed to last 60k miles - that was my only issue with the F1s.

 

I read that you already got a somewhat answer in the other thread, I'll just add this as food for thought.

A few days ago I drove My Prime with its 17" wheels/tires for about ~12 miles, then I immediately drove a stock 15" wheel/tire Prime about the same distance. Both got a mix of county roads and highway use, there was a considerable difference in feel and handling with my Prime being the stability winner.


Rob43

 

Thanks for replying. I don't think the other threads said weather runflats would help. I'm still not very clear in any case. Would changing the tires to 205/70/15 work on the Prime? Any brand recommendation? I'm seeing this instability BS is really common with corollas too, and apparently they had a TSB but I can't find a copy of it: Toyota Corolla Electric-Assist Power Steering (EPS) - Page 13 — Car Forums at Edmunds.com

Also, have you or anyone heard of the paperclip trick to reset power steering? Figured I'd ask here first before starting a new thread on that. But I've not seen any info on that regarding the prime or 4th gen prius.

 

A 205/70-15 tire would make things much worse...



Rob43

 

This would be what I'd call the middle ground between stock OE tires and an upgraded 17" tire.

Better Handling On A Budget ! | PriusChat



Rob43