Hi everyone. I’ve been searching and finding good information, but would love to get opinions on what my final decision should be. I have an 08 Prius, with 110k miles. About 70k miles ago, I bought all new tires, Hankook H727 Optimo (thanks to this group!). They have been great, amazing in the snow and I love them. I just failed my PA State Inspection on (1) front tire, and the other front tire barely made it in. The rear tires are good for at least another year or more. I was going to buy (2) new tires for the front. However… again, from reading posts from this group, I decided 3 years ago to go from the stock 185/65/15 to 195/60/15. Now, I’m seeing opinions that that may have been a mistake, that I should have gone to 195/65/15. So, if I replace these 2 fronts now, I’m stuck with the same size. Otherwise, I would replace the fronts with used tires (can’t afford all new tires right now and I have an excellent tire guy that can find me something good), and then a year down the road, I can buy all (4) new Hankook tires in the new 195/65/15 size. So I guess, the real question is, is the difference between the 195/60/15 and 195/65/15 really big enough to warrant jumping through these hoops? And as a side note, the dealer that did my inspection told me I “have the wrong size tires which is dangerous”. I scoffed at him.
We have two 2007s in the family with the H727s in the 195/60R15 size with no ill effects (and excellent snow performance). The speedometer reads a tiny bit conservatively (about 1.5 mph high at 45 mph), which might be a good thing for speed traps. Some say to use the '65 ratio to stay closer to the original rolling diameter (although the 195/65R15 is probably larger than the original) and for load-carrying capacity, but my parents and I have no complaints whatsoever with the 195/60R15 size and wouldn't hesitate to use them again.
Going from 65 to 60 is less rubber from the rim to the road. Not alot of difference but the Prius is all tire and you may notice it will hit harder over bumps if you hyper inflate the tires like some do. Less rubber to absorb the hit so it passes on that impact to the suspension and struts primarily. That and the gap from the tire to the wheel well will increase as you have shrunk the tire in its 60 size. Some people will notice this others may not. I would not mix aspect ratio's between the front and rear but you may scoff at me too.
The speedo reading high is normal for the Prius with OEM tyres fitted. In fact it is normal for most cars. Going to larger diameter tyres does help correct this. John (Britprius)