proper tire size for 15"rim on a mk3 TD to maintain accurate speedometer?

[okron1k]

i bought some corrado steelies (15" x 6" i believe) for my car a while back but haven't had the time to get some tires for it. did a bunch of research yesterday and played around with a few different calulators (miata, 1010, etc), as well as google.

according to the owners manual for a '96 jetta td, the factory tire size is supposed to be 195/60 R14. when searching on tire rack, they show that my car had 2 options, 195/60 R14 or 185/60 R14. so, my manual plus tire rack's info and i think it's safe to say 195/60 R14 is the proper size tire that the car came with from the factory. or am i wrong? the car came with 185/65 R14's when i bought it in 2011.

after some research it seems like 195/55 R15 would be the best option, but i wanted to hear other peoples opinions. i saw that a 175/60 R15 would be even closer to factory diameter, but i don't know if it is a good idea to go with a skinnier tire. i'd guess that would be a good size for a winter tire, but i'm not sure.

also, yesterday i tried downloading some free speedometer app to compare against my speedometer, and at 100 km/h the app was showing around 97 km/h. but when i enter in the factory tire size into the miata calculator as stock tire size and compare to 185/65R14 (what's on the car now), it says i should actually be going 101.1 km/h when the speedo says 100 km/h. maybe i should try it with a real gps instead of some free app.

[homerj1]

This will do the calculations for you.

http://www.miata.net/garage/tirecalc.html

[CRSMP5]

195/60 is mk3/b3 +

185-60 is 83-92 mk1/mk2

supposedly the 185 vs 195 is width.. but imo they look like a good tire vs balloon

but in theory either will work.. i do 185/60-r14 and 195/50-r15 so i can run them on both mk1s and my b3...

[ORCoaster]

If you played with the Miata calculator you know that each combination you provide gives you the diameter of that combination.  Run both suggested combos in there and then anything you want as an option and see where you fall between the stock setups. 

The difference between the 185 and 195 width combined with the same sidewall ration is nothing you will notice on the speedometer.  Or a GPS unit in my opinion.  We are talking 60% of 10 mm or roughly 1/4 of an inch in radius. 

Skinny tires cut snow and rain better than wider ones so depending on what you drive in most of the time You might consider one width over the other.

[8v-of-fury]

My brothers "winter tires" are some "for winter use only" 155/80/13 all seasons. $24 a tire at the local Canadian Tire or Walmart. AWESOME traction too. Just as good as my GF's car with brand new 3/4" lugged Nordics... And for literally 1/4 the price per tire..

[mystery3]

If you want your speedometer to actually be accurate you need taller than stock tires. Stock speedo probably reads 2-3% high. I run 185/60r14 on my mkI and the speedo is dead on. I don't know what the stock size is like 125/95/r13? They're ridiculous.

[okron1k]

If you want your speedometer to actually be accurate you need taller than stock tires. Stock speedo probably reads 2-3% high. I run 185/60r14 on my mkI and the speedo is dead on. I don't know what the stock size is like 125/95/r13? They're ridiculous.

195/55-15 seem like the right choice then, as the miata calculator shows it is 23.4" diameter as opposed to the stock 23.2" diameter. slightly taller but maybe still a little conservative, which i don't mind as much.

[rodpaslow]

I have 15's on my mK3 and I went with bigger 205/50/15.  There's only like a 2% difference.  In my case I have an adjustable (electronic) speedo, so I can change it easily if I need to.