Wouldn't a 70 series tire give a narrower tread footprint than a 65 series tire for a given size? A comparable 215/65R15 and 215/70R15 BF Goodrich Radial T/A shows a 7.0-inch tread width for the 65 series and 6.4-inch read width for the 70 series.
Technically the blanket statement that *any* tire size change will affect your speedometer reading is correct but as long as you keep the overall diameter within .1 or .2 of the original, you shouldn't notice a difference. Even with the 205/65R15 your speedometer will only read 0.1% too fast. At a real 65mph *real* speed your speedometer will read 65.65. A taller 205/70R15 is .8" taller and will make your speedometer 3.1% too slow; a 65mph reading on your speedometer would really be 67mph. I've owned a lot of 67 Chevelles and if you can read their sweep speedometers within 2mph, you're doing pretty good! :*) You might check my web page at http://chevellestuff.com/tools/tire_calc.htm. Just plug in the 195/75R14 in the Stock tire size and play with the New tire size. It'll compare Sidewall, Radius, Diameter, Circumference, and Revs per mile for each size and report how slow or fast your speedometer will read as a percentage. One should be aware that 'calculations' don't always reflect the real world and tire manufacturer's differ a bit and many tire sizes just aren't readily available. Looking at the same BF Goodrich Radial T/A chart doesn't list a 205/65R15 size but does list a 225/60R15 which is .1-inch taller and would make your speedometer read 0.4% too slow. Play with the calculator then find your favorite tire mfg and see what they offer. Dale http://chevellestuff.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, May 11, 2010 7:29 AM To: The Chevelle Mailing List Subject: Re: [Chevelle-list] Tires for my 67 I agree with your tire size selection, try to go with a 70 series size tire to widen the stance a little bit. Any tire size change will effect your speedo. You will need to change driven/drive gears once you select your tires. Darren (also known as "4-door Chevelle" on all the car forums). Stephan Bourassa wrote: > I have a 67 Chevelle 4 door 300 Deluxe. It has P195/75R14 tires on it > now with stock wheels. I want to put 7"x15 rally wheels on it. This > car does not have power steering, so I was wondering what you all > recommend for tire size that will look nice but still steers ok and > does not mess up my speedo. THX
