How will it affect handling and/or acceleration with 17"s?

Will my speedometer be off?

http://www.discounttire.com/dtcs/fin...8415&rc=FLTINT

I might buy a set of these used from someone locally. What do you think?

Not sure what size tire he has on them either... wheels and tires only have 800 miles on them.

 

depends, if the new combined wheel and tire package is heavier than what you have now, your acceleration is going to be slower due to the increase in rotational mass. braking will also be effected, but chances are the new tires could have better traction than the OEM tires, so braking distance could be a toss up, as well as handling. depends on which is greater, the increase in unsprung weight, or the increase in tire grip cornering force.

your speedometer will be off if the overal wheel and tire diameter is significantly different from the OEM wheel and tire diameter. this will also throw off your odometer, and tripometer.

 

Oh yeah... I have the stock 2005 steelies/ Hub caps right now.

 

discount tire has a tire size calculator, where you put in the OEM tire size, and the new tire size, and it will tell you the difference in diameter and how it will effect your indicated speed versus actual speed.

oh, and also, your ride will be rougher because less sidewall means less cushion.

 

A lot will depend on the tire size... kind of like drax is mentioning. Ride quality, speedo difference, etc.

 

do you think my mpg will change if I the tires are 205 45 17?

 

Well if the wheels/tires turn out to be heavier than your OEM setup, then yes, you MPG could decrease.

 

also factor in additional roll resistance, and your mpg could go down too.

 

If the overall diameter is larger than stock, your mileage might improve a bit due to gearing, which would be offset by the increased weight and resistance, so mileage would probably be unchanged overall.

If the overall diameter is the same you'll lose a little, like the guys above already said.

 

here's a calculator for ya: http://www.miata.net/garage/tirecalc.html

I've got 18s on mine, and it's pretty darn bumpy and a bit slower off the get go.

My overall tire size is nearly the same as stock though, because of the low-profile tires on there now.