Rims / Wheels 15 inch stock oem size replacement

never used them, but enkei makes decent wheels, and those aren't too heavy so it shouldn't kill your mileage. nice looking wheels. run a 205 or 215 tire that's just a tad taller than the oem's and you'll get a better speedo calibration too. speedo always reads high with the 185's.

 

He's assuming you know a little bit about tires, what to do when changing widths, and the relationship of the first parameter to the second on a tire spec.

Use a tire converter (or calculator) tool (you should be able to find one on tire rack) or google to find a calculator. Then plug in 185 (width), 65 (height ratio) and 15 (wheel size) into the appropriate boxes of the current tire parameters. Plug in 205 (or 215) into new width and 15 into new wheel size and the calculator will tell you the new height ratio (or 2) with the + or - difference (of each) when compared to the current tire.

As the height ratio is a percentage of the width (65 means that the sidewall is 65% of the tire's width), it will need to be changed as you change the width to maintain the correct overall diameter. Usually, you would decrease the height ratio as the width increases.

Hope that is clear.

 

My sense: using the stock tire size, everything except the speedo will be reasonably accurate, ie: the car's "gearing" is per spec, and the odometer will be close to reality.

The speedometer reading a bit high is intentional, there's some legislation involved, the intent being to never tell the driver he's going slower than actual, to err on the side of caution.

For anyone really in a lather of the speedometer "error", all you have to do is speed a little, lol.

 

Yes, that is correct, it is intentional and it is legislated. But the intent is to never have the driver going over the speed indicated by the speedometer taking into account things like tire wear, so it intentionally displays a speed that is lower than the actual speed. The differential is different in each country.

For example, in the UK a speed reading of 77 mph is actually 70 mph; here in NZ a speed reading of 102 km/h is actually 100 km/h. In the UK, the "correction" is a percentage (22 mph = 20 mph; 33 mph = 30 mph; 55 mph = 50 mph; etc); Here it is a straight shift – indicated speed - 2 km/h = actual speed.

These observations were both in Gen 2 Prius. Obviously it varies by jurisdiction.

 

Yeah I find our speedo fairly close: there's occasionally electrified sign posts reading/displaying vehicle speeds, and I'd find if the speedo is displaying 52 the sign post might say 50.

 

stock size tires all seem to have lousy traction compared to the 205/60R15 yokos and Michelins I had before I got my 16" wheels. 205/60 is a little taller than the 185/65's. and I still got 50mpg in the summer.