Date: Mon, 08 Mar 2004 17:59:26 GMT From: Bob <uctraingNOSPAMnospamanet.com> Subject: Re: wheels on 900s
On Fri, 5 Mar 2004 23:36:23 -0500, "Jody Burke" <jodyburkenospamsouth.net> wrote: >I was interested in putting a larger wheel on my 95 900s convertible. I did >some calculations with info from the tire rack site and the wheels and tires >I am considering would give me an extra inch in diameter. Does anyone have >any experience as to how much this increase would affect my speedometer and >final drive ratio? Thanks in advance for any assistance! First, the goal of larger wheels is to reduce tire sidewall height to stiffen the tire and increase handling. SO, you shoot to maintain the same overall diameter whenever possible. Here's a calculator that will give you the speedo error: http://www.miata.net/garage/tirecalc.html Do you have 15 or 16" wheels now ? You can go to a 16" wheel and still be at a stock size. You will do what's known as a "plus 1" upgrade, changing the wheels to 16" and the tires to 205-50-16. You might need to have the dealer tweak the computer depending on what you are running now for tires. If you want to go to 17", you would do a similar upgrade, changing tires once again to maintain speedo accuracy. (I'm not very fond of 17" wheels on the street in places with holes in the roads and frost heaves. ) It's a little hard to find 205-50-16 tires if you need all season's so some of us go to a 205-55-16 and take on a little speedo error for a little more ride comfort and better tire availability.