What effect from tire size and type?
 

Just wanted to throw this out here. My '94 Caravan has been running on 215/70R14 Indy 500 Firehawk performance tires for about 3 years now. The original tire for the van was 195/75R14, a normal passenger type radial. I've since returned to the original tire size over the last two weeks since the wider tires seem not to like being under the van. Does anybody think that difference in size would have a large effect on the FE, especially going from a performance oriented tire to an original style passenger tread? The new ones are Bridgestone Insignias. Any thoughts?

Aaron

PonchoBuick -

I went here :

(Miata) Tire size calculator

And made this comparison :

http://ecomodder.com/forum/attachmen...6&d=1226955282

I also went here :

Car Bibles : The Wheel and Tyre Bible Page 2 of 2

And got the same result :

http://ecomodder.com/forum/attachmen...7&d=1226955775

From the above, the revolutions per mile look very close. Still, I think you should do a GPS comparison to your odometer. That's what I have done :

http://ecomodder.com/forum/showthrea...ires-2642.html

I am not sure how to quantify the width, but I agree that performance tires have a bigger contact patch and are more sticky (increased Rolling Resistance). Because the tire diameters are so close, I think you made a good choice.

CarloSW2