Tires for a '90 Miata

Some manufacturers make a P195/55 r14. I'm thinking that the 55 series might be a closer match to the original circumference but I couldn't say for sure.

Chris

Personally, I don't really care about any of that. I calculate the speedo error with mileposts and a stopwatch, and pay little attention to the odo. Actually, with 205/50-15 my speedo is almost perfect. But every Miata is a little different.

not exactly what you are asking but if you are in the northern hemishere, it is getting to be winter, get some nokian hakka's. the differnece is amazing in the snow.ice.

peter

Is there a typo here?

I'm no expert but my understanding is that 185 and 195 indicate the tread width in millimeters. In other words, you are getting a tire that is about 2/5 of an inch wider. This may provide slightly better grip in cornering, everything else being equal. (Tread pattern, compound hardness, tire pressure, slip angles...)

But since they are both 60 profile I think the diameter will be exactly the same, hence the speedo/odo will not be affected.

cheers

Don

It's true that that 185 and 195 indicate the tread width. However, the

But there WAS a typo there: I was looking for good thread-wear, not good thread-ware...

Thanks!

Ummmm... ...no.

The "60" indicates that the section height of the tire is 60% of the section width of the tire (the "185" or "195" in the size; which is not tread width, BTW), and both of these figures are nominal and not necessarily completely precise.

So a 185/60R14 tire is (nominally!) 185mm wide at its widest point (the tread is narrower and (nominally!) 2 * (185 * .6)/25.4 + 14 = 22.74" tall.

1. 185 and 195 indicate the *section* width, no the tread width.
2. The 60 indicates the ratio of the section height to section width as a percentage

I was just tinking te same ting....

In fact, there is a great variance from manufacturer to manufacturer and from tire model to tire model. On the company "Tire Rack"'s site, you can compare the specifications of tires, and see that some tires two full metric sizes apart (typically 20mm, or about 4/5's of an inch) will have the same tread width, and the smaller section width tire may even have greater tread width in some rare instances.

Yup. But all other things being equal, the narrower section width will typically have the narrower tread.

Ask nicely, and you might get your aitches back. :)

Strictly speaking you are correct of course. However, 60% of 185 versus 60% of 195?

Without going into heavy (for me) math, I will speculate that the difference in diameter will come to about 2%. If I'm going 51 and my speedometer is showing 50, I can certainly live with that margin of error.

cheers

(195-185)/195 = 5%

Using stock tire sizes, my speedo is off by 8-10% at freeway speeds, so a 2% correction is hardly worth considering. A 5% correction is a little better.

As many do.

I just made that exact tire change you mention on my '99 Miata. I went to 195/60 14's. I wanted a bigger tire and to get the car off the ground a little more. And the tires do look better, but the amount it raised the car is hard to tell getting in and out of it. But I will say it made a drastic difference in the handling. Not quick and tight in turns like it was before. It more does a swerve in turns than the quick instant turns it used to. Now I'm a true believer in short sidewall height for better handling. I wouldn't go back to the original tire size on the next set though, I'll be shopping for some

the speedometer would indeed read 2% too slow if going from a 185/60/14 to a 195/60/14. our beloved miata.net website has a handy little calculator for this:

Instead of 5% too fast, as it did originally?

In truth, every Miata speedo seems to be off by a different amount, so it's a good idea to check it with a stopwatch or GPS. Don't expect the percentage to be constant over its range, either.

Mine seems fairly close with 205/50-15. More or less. But now the odometer is off.