larger tire size causing instability

OEM on the 2009 Prius Touring is 195/55/16 and it's very stable...as well as a size that's in limited supply.
I suspect that MPG might suffer a very small amount but that's about all.

 

Wider tires will tend to try to climb out of wheel tracks in the road more than narrower ones, and many interpret that as instability. It is not.

 

I ran 195/60/15 Michelin Exalto A/S on my 2005... zero issues. Super sticky tires, lost 2-3 mpg or so because of the thread compound, not sizing.

 

Less stable? Not in my experience. The 195 TripleTreds I'm using now are so much better than the 185 Integrities that I'd say the stock tires are borderline dangerous.

 

Guess it depends on what you mean by "instability". Wider tires can "tramline" more than the OEM size but this is usually only much wider tires. I have used 205/60R15 tires on my 2005 for the last 40,000 miles and have had no issues.

 

I am looking at replacing OEM tires as purchased vehicle used. I purchased it with;one tire brand new, one that was pretty worn and two rears which are about half way home. Considering I purchased w/26K miles don't think I'm losing a lot by replacing all 4 now and the handling is poor the brand new is paired with the mostly worn tire together on the front. I assume a "throw a tire on" job to pass inspection was the culprit. I am also quite certain it needs a 4 wheel alignment. Anyhow were you able to get the larger tires you're using done at a National chain (like Goodyear or NTB) or did you do it yourself/or at local garage? I see you've driven, or are still driving, some of the higher end cars. I traded a BMW for this car and obviously knew handling would take a big hit. However I am positive a better and larger tire can offset some of what I'm feeling (or not feeling). Looking to upgrade to good A/S and larger tire this weekend and am loading up on info. Thanks for any and all input ....Joe D

 

Joe: The 205's certainly improved handling. The Prius was my wife's car but I drove occasionally. Just try to get tires that don't give away too much in the ride (the Potenza's supposedly have a good ride but they were way too harsh for my liking).

 

I just put four new Michelin Harmony 195/60/15 tires on my 09. Rides nice. Can't say I notice anything other than that "new tire" ride. Which is exactly as I expected. Out the door at $545.00 Got about 27k on the OEM tires and they were getting fairly close to the tread wear indicators but too low for my comfort as concerns water dispersal capability.

 

Thanks guys. I am thinking that I need to be smart and invest in good A/S tire and think a bit larger would just make the car feel more stable to me. The real thing that would probably help would be a sway bar coupled with new (larger and better) tires. I don't need it to be ready for a racing circuit by any means but would just like that "solid" feel under me when driving. I love the car. My first attempt at using gas saving techniques was pretty successful for a novice. My mpg increased by 8mpg to a 48.8 average and 481 miles on the tank. I have been using A/C liberally as it's been 95 degrees here for most of June. My Beamer was making it about 310 miles on 16 gallons or so ....around 19mpg....so this is a wonderful change. My fill up today did take 11 gallons so I was walking the line from what I know of the "bladder" gas tank and it's 11.5 capacity. I am happy w/the car in so many ways but want to like the ride...not just like the ride

 

195/60/15 Hydroedges, and a BT Stiffening Plate on ours completely resolved the handling issues we had when we bought it.

Our Prius is now stable, handles excellently in bad weather, and we'd certainly do it again!