Rim/Tire Size ?'s.....

[a94civicex]

So I need to know answers from all the tire/rim size people on here & maybe I will get the answers I'm looking for:

I'm currently running 99-00 si wheels with 205/50r15's & need to know if 205/40r16's are basically the same circumference in size? Or will it be really close because I'm planning on trading my si's for some 16" gt3's tomorrow!

LMK ASAP PLEASE!

[allout13]

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

[Humphrizzle]

my tire sidewall measurement formula

ex. 205/40/16

first number is the width of the tire in millimeters

second number is a percentage 40% of 205 is the size in millimeters your sidewall measures

third number is the wheel size

40% of 205 is 88mm and is about 3.2 inches

16 + 3.2 + 3.2 = 22.5 inches

ex2. 205/50/15

50% of 205 is 102.5 which calculates to 4 inches

15 + 4 + 4 = 23 inches


The answer: ^^^^^

[a94civicex]

205/50-15 4.0in 11.5in 23.1in 72.5in 874 0.0%
205/40-16 3.2in 11.2in 22.5in 70.5in 898 -2.7%

This is what I found out!

Does this tell me that they are a tad bit smaller than my current setup?

[Humphrizzle]

read my fucking post!!!

[a94civicex]

read my fucking post!!!

Lol, it doesn't matter anymore now, my 205/40r16's are a whole lot smaller than my old 205/50r15's setup!

Thanks for your input & hostility, lol

[Bacon]

Used the calculator from 1010tires.com 205/40-16 is in red

Stock Tire - 205/50R15 Tire 1 - 205/40R16
Section Width: 8.07 in 205 mm
Section Width: 8.07 in 205 mm
Rim Diameter: 15 in 381 mm
Rim Diameter: 16 in 406.4 mm
Rim Width Range: 5.5 - 7.5 in
Rim Width Range: 7 - 8 in
Overall Diameter: 23.07 in 585.97 mm
Overall Diameter: 22.45 in 570.23 mm
Sidewall Height: 4.03 in 102.36 mm
Sidewall Height: 3.22 in 81.788 mm
Radius: 11.53 in 292.86 mm
Radius: 11.22 in 284.98 mm
Circumference: 72.47 in 1840.7 mm
Circumference: 70.52 in 1791.2 mm
Revs per Mile: 901.6
Revs per Mile: 926.5
Actual Speed: 60 mph 100 km/h
Speedometer1: 61.6 mph 102. km/h

Speedometer Difference: - Speedometer Difference: 2.761% too fast
Diameter Difference: - Diameter Difference: 2.69%

[Humphrizzle]

HOLY FUCK! you dont realize my post contained the answer?

[a94civicex]

HOLY FUCK! you dont realize my post contained the answer?

NO KIDDING, it was too confusing so I found it myself!

[Bacon]

HOLY FUCK! you dont realize my post contained the answer?

I can read. However, my post also shows the MPH difference between the two so that he knows what to expect.

[Humphrizzle]

Lol math is too hard I guessssss