Tires - 185/65/15 OR 195/60/15

<div class='quotetop'>QUOTE(Mary Lou In Ohio @ Dec 29 2006, 09:55 AM) [snapback]368254[/snapback]</div>

Well, if I remember correctly, 185 is the width of the tread in millimeters, 65 is the hight of the sidewall expressed as a percentage of the tread width (65% of 185 mm = 120 mm) and 15 is the diameter of the wheel in inches. If you apply this formula to the two different tire sizes, the 195/60 wheel has a sidewall of 117 mm, slightly smaller than the 185/65 tire, thus the 195/60 wheel will make more revolutions per mile than the 185/65 wheel and will result in a small, artificial increase on your speedometer display (but only a couple of percent). People typically get the wider (195 mm vs 185 mm) tires for better traction on dry roads and a better, more connected-to-the-road feel and look of the car. However, the wider tire will apply less pressure per square inch onto the pavement, so in snowy or wet conditions where you want the tire to push through the snow or water, a wider tire might give you less traction. The manufacturer typically matches the width of the stock tires to the weight and projected use of the car, which is why you typically see wider tires on sports cars for better traction which is needed with increased power. You can't go wrong with the manufacturer's tire recommendations, but going to a 195 width tire will not have any significant detrimental effects. And you may like the look of the wider tires and the way they seem to "stick" to the road on turns. I wouldn't think that going to the 195 tire will significantly affect your mileage, but I am a new Prius owner myself and some of the other guys may correct me on this.

 

As stated, the 195s will have a bigger contact patch; i.e., more rolling resistance.

 

have HE's on the wife's 2k4 and they are slightly noiser than the stock G I's wet traction is really good and tracking is noticeably improved. Mileage has taken a slight hit but I had them installed just before the cold weather arrived along with winter blend fuel so can't say for sure if they are the total cause of it. We live in a rain forest and if your needs are similar they would be my first choice but if you in a dryer and warmer local the MX4's are a good choice.

 

Tire manufacturers will provide you with a number called revolutions per mile. This number needs to be fairly close to the original tires. The Goodyear Integrity 185/65-15 is 855 revolutions per mile. I like to stay within 1% of that but 2% is probably OK. You may find, if you want a wider tire, that a 205/60-15 comes closer than a 195/60-15 in most tires but you should check that number on each type you are considering.