Correct Z tire size

[Phacade]

After a long bit of research I have finally concluded what I believe to be the correct tire size for '70-'78 model Z's. They origianlly came with a 70 rated 14" tire, usually a P185x70x14. Of couse this varied depending on the dealer of course. I have dabbled with 15" and 16" wheels, and yes, even with 17" wheels on my 240z. Nissan designed it to be a 14" tire. To go outside of this will mess with speedometer reading, and other things as well. I have even heard it will affect braking. In any case, I now go with, and recommend, a 60 rated 14" tire. My exact size, P215x60x14, all the way around. It gives me the look I want (low profile), performance (lower side walls = better cornering). I have seen a few even go with a P235x60x14. Too wide in my opinion. Technically, it will fit. Bit it will also rub in the front under hard cornering. Try not to go lower than a 60 rated tire, however. This will, once again, throw off your speedometer, and will also increase ride harshness (and thats no fun). Brand? I went with BF Goodrich personally, although Goodyear makes a good tire, as does Pirelli.

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"Go into emptiness, strike voids, bypass his defences; hit him where he does not expect you" -Lao Tzu

[visionary]

Hey Timberwolf,

I have been agonizing about tire sizes and profiles for my next set. Currently, I have 195x14" on 14"x6" rims. I like the goodrich radial TA and I think I will take your advice and stay with the 14" rim but do not know what the width limitations and/or optimal setup is. Any advice on rim width?

Keith

[simple_old]

IMHO the correct tire size for the 240 and 260 was a 175R14 on a 4.5 or 5 inch wheel. The 280Z used a 195/70R14 on a 5 or 5.5 inch steel wheel or a 6 inch alloy. Both these tires are approximately 25 inches tall. The 215/60R14 that you are talking about is about an inch shorter. The 235/60R14 is much closer to the stock height but like you I think much too wide.

[PetesPonies]

guys, it's not the size or profile that is important or wrong, it's the overall tire diameter, or circumference. If you keep that the same, your speedometer wil always be correct. Just like changing the rear end gear, a different speedogear on the cable will solve sppedo error anyway. Take the section width of the tire ex 215. Multiply this by the aspect ratio 215 X .60 = 129mm. Multyiply this by 2 ( two sidewalls ) and then divide by 25.4 ( to convert to inches). 258 / 25.4= 10.15. Add the wheel diametter to this 10.15 + 14 = a tire that is 24.15 inches tall( diameter ). A stock 175 /70/14 was 175 X .70 X 2 / 25.4 + 14 = 23.6. So a 215/60/14 is .55 or 1/2" taller. The 195/70/14 is 24.7 tall. You can go to 15" or 16" tires and keep the same height, just use lower profile tires.

[Dan Baldwin]

Stock size was not 175/70-14. More like 175/80-14. Stock diameter was ~25".

215/60-15 is about stock diameter, 215/60-14 is an inch shorter. I run 225/50-15s on the street, more than an inch shorter than stock. At the track, I run 225/50-14s, WAY shorter than stock. Benefits include: lower c.g., less rotating and unsprung mass, better (for performance) overall gearing, better braking response (more braking for a given effort at the pedal).

Impossible to find GOOD 14" tires that are stock diameter these days. Tire Rack has a good site for comparing tires, check it out. I just got a set of B'stone S-03 Pole Positions from them, one of two top-of-the-line performance tires available in 225/50-15 size, the other being the Pirelli PZero.

Don't worry 'bout that speedo error, but do be aware of it.

[PetesPonies]

no such thing as a 175/80/14 tire

[Dan Baldwin]

Size was 175-14. Effective aspect ratio was indeed on the order of 80%, though that wasn't included in the tire size in those days. No new tires available in that size, that's for sure.

[PetesPonies]

I believe the 280Zs came with a 195/70 . Assuming that it was supposed to be the same height, you are looking at 24.7" tall. Aspect ratios on old tires were 78, not 80. Plug a 78 ratio into a 175 tire and the overall height is 24.7", exactly the same height as the 195/70 -280Z tire.

[Dan Baldwin]

Tires are almost never exactly the size/AR on the sidewall, lotsa variation. For the record, years ago, I measured a 215/60-15 Yok A509 and my stock, barely-used 175-14 Toyo spare, and they were both just over 25" in diameter. I know they often refer to old tires as 78 AR, but generally speaking, actual tire aspect ratio vs. advertised is on the order of as much as +/- 5% for new tires, probably more variation from 78% for old tires. Anyway, I'll stand by my comments that the stock 240 size is "more like 175/80-14" and that aspect ratio was "on the order of 80%":)

Tall, skinny, ugly tires, even by the standards of the time. And those hubcaps, yikes!

[simple_old]

You are right on the size variation. The size on the side of the tire is a nominal number much like a "2X4". The actual heigth can vary up to an inch (more commen in truck sizes) and depends on the manufacturer and even varies between styles of the same manufacturer. The old metric sizes without an aspect ratio (i.e. 175R14) were usually 82 series. 80 series tires didn't appear until US manufacturers brought out the P-metric sizes and were only in the 13 inch sizes (i.e. P165/80R13).

[Saint]

Question..if I was to purchase a set of Panasport 16 x 7" wheels for my yet to be completed 1971 240z what would be an appropriate tyre choice?

[Royce]

Sorry, I don't know what tires are available in the UK for that size rim. Generally speaking a 7" rim can fit a 195 - 245 size tire. If you are looking for good performance and go with a 50 or less series tire I would probably say a 225 would be the best bet, but check with the tire manufacturer to see what they recommend. Also, if you are really looking for high performance for track or autocross I would suggest having the tire heat cycled and shaved. It will add $$$ to the cost of the tire which would be a waste for just street driving. But you will get more performance and actually longer usable life from the tire in competitive situations.

Have fun!