I have an early 1971 240Z with a stock suspension and American Racing 14"x7" mesh wheels.  I am presently running 195/70R14 Goodyear Eagle tires that have aged out (30 years!) and need replacement.  The Goodyears have a slightly smaller diameter than the original Toyo 175HR14 tires so the revs are higher than originally intended (inaccurate speedo as well).  I'd like to go to a slightly larger tire to "correct" the speedo and reduce the revs when cruising.  A 205/70R14 would fit the bill except that I've heard that with early cars they may rub when making turns.  I don't want to do any body mods as I'd like to keep the car body stock.  Does anyone have experience with the 205s on their '71 cars?   BTW, the original Toyo measures about 25.5" in diameter, and the aspect ratio calculated to be about 83%

not what you asked but I like my 185/R75's Speedo is very accurate, looks period correct. If I was doing it again I would get these on the stock steel rims

https://www.cokertire.com/tires/175hr14-vredestein-sprint-classic.html

I had two different brands of 205/70 on my 76 and one set rubbed and the other didn't.  The car was slightly lowered though, and the rubbing only happened in the hard twisty/hilly cornering.  And it wasn't terrible, just the occasional ZZZT  ZZZT on a bump in the corner.

Do you think that the small change in diameter is going to have that big of an effect on revs and speedo?  Have you used a calculator to verify?  Seems like you'd barely notice.

Most people buy their tires to make the car look right.  

Here's a neat calculator.  Takes some work to figure out which boxes to check though.  It has a slider for RPM to pick your MPH.  There's a tire size input area at the bottom.  Then you have to "set" it.  But the results and graphics are fun.

https://www.blocklayer.com/rpm-gear.aspx

Edited September 29, 20204 yr by Zed Head

I ran 195/70x14 Pirelli tire for many years on 14X7 slotted wheel without issues on My lowered 71. Speedo was pretty accurate back then. Now we know with GPS that they probably weren’t.  Do not know the offset of  those wheels that were a dealer installed item. Currently I am running 205/60x15 on 15x7 VTO on the same setup. MPH on slightly high at the speedo. also an Close ratio 5 spd and 3.90 LSD

Which takes me back to what @zedhead said go with what looks good to you.