Skid Ind. & Tire Pressure lights, car balks at highway speeds

Hi all. New here—I hope you’ll be kind!

I bought my 2007 Prius used last year. As of now, it has just short of 126,000 miles. I replaced both the hybrid battery (that cost a bundle) and the standard battery this July—so, about six weeks ago. I also had the annual (PA) inspection done in July.

I’ve been doing a lot of highway driving—I’m in the middle of a road trip, more or less—and about a week ago, while on the highway, I started experiencing some weird jittering within the vehicle. It’s hard to describe it better than that, except that I assumed it was a tire issue, possibly sustained when I had bumped over a high curb earlier that morning. In fact I was so sure I had a puncture--probably in the right front--that when I pulled over to have a look, I was surprised that I couldn’t find anything obviously wrong.

I got back on the road, and the jittering continued; it got really noticeable when I went over about 55 or so, so I rolled along at low-ish speeds for the rest of the day.

As I mentioned, I’m on a road trip, so not near the dealer I purchased from, and sometimes I’m not near any Toyota specialist at all. On the advice of the friend I was staying with, the next day I went to a local Mr. Tire. I described to them what had been happening, and asked if they could balance and rotate the tires and let me know if they found anything obviously wrong.

When I went back, they told me that they had found that “the metal belts are broken in three out of your four tires--you can see the obvious bumps,” and offered to replace all four tires for $800.

I expressed my surprise, given that the car had passed inspection six weeks earlier and no one had mentioned any tire issues. The Mr. Tire staff looked confused. For some reason, no one was able to locate the person who had actually looked at my tires. I went to get a second opinion.

At the second place I went, they actually did rotate and balance my tires (the first place had decided not to do that, “since you would still have the vibration”). This time, I didn’t give the backstory up front. After the rotation, they told me that my struts and shocks needed replacing, and offered to do it for $1,000. I asked if they had found anything wrong with the tires themselves. They looked surprised, blinked, and said, “Well, I mean, you should replace them sometime, sooner rather than later…” (It’s true that the tires are old; I just don’t want to replace them *right now* if I don’t have to—especially not if there’s a different actual problem that will cost money.)

So as of now, the situation is that:
a) Things still feel weirdly jittery at higher speeds,
b) The Skid Indicator/ Traction Control light flashes on and stays flashing at frequent though not always obvious intervals (sometimes it’s at higher speeds and/or in the rain, but sometimes it’s at 50 mph on clear dry road),
c) As of today (this is a new development), the Tire Pressure light is also on steadily,
d) As of today, the car *will not go* above a certain speed. I can’t say exactly what that speed is, because it seems to vary, perhaps depending in part on whether I’m on an upslope or a downslope. Today I was in the slow lane on a mountain highway, and the car refused at one point to go above 42 mph when I was on an upslope; then again, it was happy to get to 60 or 65 when I was going down. When this is happening, the Skid Indicator/ Traction Control light is doing its constant-flashing thing.

I’m trying to get some kind of sense of a) what may actually be going wrong here, b) whether I’m endangering myself and c) whether I’m risking damaging the car by continuing to drive. I don’t have a death wish—if the car won’t go faster for safety reasons, then I don’t *want* it to go faster; keeping to low speeds and avoiding highways for the moment is inconvenient, but, you know, better than blowing out on the road.

Part of my problem, though, is that I can’t just “take it to my dealer tomorrow”: as I mentioned, I’m traveling and far from home. Another problem is that, as a solo woman, I am, depressingly, extremely used to being quoted high prices for fixes that don’t sound like they have much to do with my actual problem, and then not being taken seriously when I ask questions (see example 1, Mr. Tire, above). I want to inform myself as much as possible, to defend myself against being taken advantage of. I’d also like to maximize the chance of being able to actually address this problem, ideally with the minimum fix in terms of cost that will still let me get where I’m going. (I’m crossing several states for pandemic-related reasons--so, kind of a road trip and kind of a trying-to-get-somewhere situation.)

I bought a code reader, and I figure I’ll use that tomorrow and see what comes up. Also, in a couple of days, I’ll be in a more urban area with Toyota-specific mechanics and dealerships, so I figure I can take it in to one then if the problem persists. Again, though, before I go, I’d like to be as well-informed as possible! (And also figure out if I should be on the road at all.)

Thanks for any help!