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[cdgatti]

This is a question for the moderators of this site. Can the wording of the computed output of the tire size calculator be modified? I think it rather confusing right now in how it reads.

This is what it currently says:

Speedo @60mph will read: 58 mph as an example

I think it would be more clear to people if it was re-worded to read:

When the Speedo reads @60mph: the car will be traveling: 58 mph

[Reckless335]

I'm not sure, but I think you have them backwards. The way I read it currently (like your example)
"Speedo @60mph will read :58mph" I read that as follows: When the car is going 60mph the speedo will only say 58mph.

However, I do agree that the opposite would be beneficial to list as well. In this particular case (speedo is faster by 2) so I think the calculator should list the following:

"Speedo @60mph will read :58mph" and "When speedo reads 60mph, vehicle is travelling 62mph"

See how this could be beneficial? Often times I'm forced to do the math the inverse of what's given by the calculator. Usually I'm trying to use the calculator to correct the speedo, rather than create more problems for it.

[cdgatti]

no my friend I think you have it backwards... not wanting to get into an argument, but if you do an example where the new tires are smaller diameter than the old you will see that with the speedo at 60, it will compute a lower number, which is the speed of the car. let us know how you see it after doing some examples with smaller and larger new tires.

Just use this calculator instead: http://www.miata.net/garage/tirecalc.html

[bmw325i]

It is kind of confusing. It should say, when the vehicle is going 60 the speedo will read.....

The speedometer is 3mph over from the factory so larger diameter tires will make it more accurate.

[Reckless335]

Smaller tires make your speedo read MORE than actual speed. Since they have a smaller circumference they need to turn MORE revolutions to keep the same distance. For example. Let's compare a 15" wheel to a 20" wheel. So, lets say those are the circumferences for the sake of this argument. So in 1 revolution the 15" wheel travels 15 inches. the 20" wheel travels 20 inches. So let's start multiplying. In 2 rotations the 15" travels 30 inches, and the 20" travels 40 inches. Etc etc. So. lets take 5 rotations of the 20" wheel. that's 100 inches. In order for the 15" wheel to cover 100 inches. It would need to turn 6.6 rotations. Think of rotations as the speedometer. Same distance (100 inches) but with the 20" wheel the speedometer is reading 5 while the 15" wheel, the speedometer is reading 6.6 So, smaller wheels = higher reading on the speedometer, and larger wheels = lower reading on the speedometer.

[cdgatti]

im an engineer you don't have to explain this stuff to me! my argument in first post still holds.

[bmw325i]

Originally Posted by cdgatti

im an engineer you don't have to explain this stuff to me! my argument in first post still holds.

Actually you are right. The way it is written now is backwards from how it's should be.