15" to 14" rims

[*MAD DOG*]

I had 15" inch alloy mag rims on my Yaris, I purchased a set of 14" stock steelies from a member on here who had them on his 09 Yaris. I've since put them on my car. I've found that by going from 15" to 14" has caused by speedo to be incorrect. My speedo says i'm going faster than what I really am.

e.g.

To go 100km/h i need to travel at 108km/h on the dash speedo
To go 90km/h i need to travel at 99km/h on the dash speedo
To go 80km/h I need to travel at 88km/h on the dash speedo

So you won't get into trouble for speeding if you follow the dash, but you will wonder why the whole world is passing you. Of course the other bummer is if the car thinks it's going faster than it actually is it is also putting more km on my dash display than necessary and also means I have to service sooner to keep my warranty.

[thebarber]

Originally Posted by *MAD DOG*

I had 15" inch alloy mag rims on my Yaris, I purchased a set of 14" stock steelies from a member on here who had them on his 09 Yaris. I've since put them on my car. I've found that by going from 15" to 14" has caused by speedo to be incorrect. My speedo says i'm going faster than what I really am.

e.g.

To go 100km/h i need to travel at 108km/h on the dash speedo
To go 90km/h i need to travel at 99km/h on the dash speedo
To go 80km/h I need to travel at 88km/h on the dash speedo

So you won't get into trouble for speeding if you follow the dash, but you will wonder why the whole world is passing you. Of course the other bummer is if the car thinks it's going faster than it actually is it is also putting more km on my dash display than necessary and also means I have to service sooner to keep my warranty.

should have bought tires that match your oem sizing...thats not the wheels' fault

[*MAD DOG*]

Originally Posted by thebarber

should have bought tires that match your oem sizing...thats not the wheels' fault

Both 15" and 14" are oem if you bothered to read my post.

[ozmdd]

Originally Posted by *MAD DOG*

Both 15" and 14" are oem if you bothered to read my post.

Yes, but you are not running correct rubber, meaning the OD is smaller. Yarii do come with both 14 and 15 wheels oem, but they run similar OD tires to match the speedo calibration.

[thebarber]

Originally Posted by *MAD DOG*

Both 15" and 14" are oem if you bothered to read my post.

i did bother, but if you knew to size your 14" tires to match your 185-60-15 tire size, you wouldnt be 3.5% off in YOUR oem rotating diameter running 175-65-14's. its simple math to figure out they arent the same diameter. since 185-60-14 =~ 175-65-14, you're actually 1/2" LESS rubber on your sidewall, and thus 1" shorter overall.

its a post i've made before since my car came with 14's and i mentioned that the speedo seems off according to gps (again confirmed this weekend going up north)

i think all yaris speedo's are set to 185-60-15 sizing, not 175-65-14.