Just got new tires...now car feels "floaty"'on road.

Check your tire pressures. Costco probably only inflated them to the door jamb sticker pressures.

 

There is usually some "burn in" time for all new tires. The distance varies depending on brand and conditions, and you can likely count on them being settled in by the time of your first rotation. How did the old tires look? Were they evenly worn? I suppose it is possible for new tires to accentuate worn suspension parts. Oil leaking out of your struts means they are toast. An alignment check would reveal what might be worn elsewhere. How many miles on the clock?

 

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Just got new tires...now car feels "floaty"'on road. | PriusChat

SCH-I535

 

Tires are safe up to the max cold pressure stamped on sidewall. Probably 44 psi, but check sidewall for sure. Not familiar with Ecopia. Most believe that fronts should be 2 psi higher than rears on Prius for handling.

 

most people use 40 front/38 rear

 

The EP422s are known for this. Really lousy tire according to the Tire Rack testing and user reviews

 

'What should they be' is a matter of personal choice. It is mostly a tradeoff between comfort and handling and tread life and mpg. Many of us take the door label numbers as minimum, sidewall numbers as maximum. The door label number gives better comfort, the sidewall number gives crisper handling, slightly better mpg, and often better tread life, at the cost of a harsher ride and possible earlier suspension wear. You pick your own poison, selecting whatever number in that range works best for you.

There are also traction and traction-safety issues, but these often devolve into near-religious discussions lacking consensus.

 

If you always use the same tire size indicated on the door label, the auto maker has determined that "X" PSI is the ideal pressure for:
*Ride,
*Load Capacity,
*Traction/Wear,
*Fuel Economy/Rolling Resistance.
Source Link

As Kenoarto pointed out, there are probably a lot who do 40 PSI front, 38 PSI rear. Whatever number you decide, keep the rears 2 PSI lower.

Art's Automotive recommends 38PSI (assumed front and 36PSI rear). LINK

This link goes into a good explanation about over inflation. LINK

A Prius Chat thread on PSI; good read. LINK

 

Maybe the worn out suspension is the actual problem here? The OP knew it was past it and then if had been allowed to hang low on the ramp whilst new tyres were fitted it could exacerbate the problems.

Get your suspension fixed. Usually it's the cheaper parts that fail first so it should be that much of an expense. But it's a safety issue - sort it

 

It likely is the tread pattern. Do they have center grooves that go all the way around the tire ??
I had a set of Michelin Hydro-edge tires on a Caddy that I just absolutely HATED for that same reason.

 

I got the same ones to replace my worn out Michelin's ( have had tire issues). I have the same issue. At first I thought something was wrong with my car, it was raining and slightly windy. We all know the wind push-pull with the Prius but this was crazy I was all over the road. For several weeks I hated driving on them because we had lots of wind at that time but I have gotten used to them, Would I buy them again? NO. I loved my Michelin Defenders but I worn them out in less than 23000. Same with Nokians WGR3's. Not sure what will be next. I have a 2004 with 151,000.

 

Well - if you look at the Tire Rack user reviews and filter on Toyota as a brand, the comments from Prius owners are generally pretty good. I personally have no issue with the Ecopia EP422 and plan to buy another set for the 2004 in the next couple of weeks from Costco here in Tucson.

I agree that it would help to increase tire inflation; I use 44/42 psi.

I've also found that tire tread wear has been the best with the EP422 compared to other tire brands/models I've tried with the 2004. I'll probably get ~50K miles with those tires, replacing them when the tread depth becomes 3/32".

 

Maybe, maybe not.
If the problem is with the tread pattern (or lack of) in the center of the tire, increased pressure might make it worse.
Worth a little experimentation though.

 

I had a set of Ecopias installed on my 2005 Prius at costco. The car was squirmy, and the wind from semi trucks st freeway speed would make the car go offline, even while driving alongside one. In short, I played with tire pressures, but no luck. I went back to Costco and had them replaced with Michelens, problem solved. Costco has a 4 week return period on tires, at least with these tires at that time they did. I thought these weren't just bad tires, but unsafe.

 

Weird. I have the OEM Ecopia EP20 (3rd gen) and they are not bad. I would imagine EP422 were better and not worse?
Is second gen too heavy for them?