New wheels now what about the the speedometer being off?

[Kuntryboy865]

I got me some 16.7 sparco wheels, now im wondering if my speedmeter is off and how to fix it if it is.

 

[Natesriv]

Wait....not 17" but 16.7"?

 

[tDubs]

Use this calculator http://www.discounttire.com/dtcs/infoTireMath.dos. Put in orig tire size, then new tire size, will tell you speed difference at various speeds if any. It won't be exact, all wheels/tires being slightly different, but it will give you a rough idea.

If it is off, I've heard that trifecta can adjust your tune to account for new tire size in the speedo. But I havent done it myself and can't say for sure if it is just something I think I remember, or something that actually existed on the interwebs.

 

[Kuntryboy865]

Wait....not 17" but 16.7"?

they were 99 bucks and within my budget so lol.

Use this calculator Tire Dimensions Made Simple - Discount Tire. Put in orig tire size, then new tire size, will tell you speed difference at various speeds if any. It won't be exact, all wheels/tires being slightly different, but it will give you a rough idea.

If it is off, I've heard that trifecta can adjust your tune to account for new tire size in the speedo. But I havent done it myself and can't say for sure if it is just something I think I remember, or something that actually existed on the interwebs.

cool i'll check it out.

 

[ahtoxa]

Got a link to the ones you got? Curious about the size

 

[Preloader]

16 x 7, I'm guessing.

Simple way to find out how far it's off. Download a free GPS speed app for your phone. Drive at a steady 65mph according to your speedo, and take note of what the GPS says.

If it's +/- 2mph, I'd just live with it. If you have a Trifecta tune, you can log, and send it in with the info. Tell them how fast your speedo says when GPS tells you you're doing 65mph, or vice versa.

 

[Kuntryboy865]

Got a link to the ones you got? Curious about the size

https://www.tirerack.com/wheels/Whe...Sonic+Hatchback&autoYear=2013&autoModClar=LTZ

 

[sx sonic]

Nice rims! Looks like they're probably 16 by 7" wide like Pre said.

They won't effect your Speedo but the tires you choose could.
You need a tire with the same outside diameter as stock. The tire calculator that's been posted will give you that dimension if you enter in your stock tire size.

Then just play around with new tire dimensions and see how the compare (you can do that with the tire calculator comparison).


If for whatever reason you go with a tire that has a bigger or smaller O.D. Vince should be able to correct it just by knowing the tire size (eg 245/50R17). I know it can be changed very easily with HPtuners and I imagine Vince can do it equally as easily.

 

[Natesriv]

16 x 7, I'm guessing.

Simple way to find out how far it's off. Download a free GPS speed app for your phone. Drive at a steady 65mph according to your speedo, and take note of what the GPS says.

If it's +/- 2mph, I'd just live with it. If you have a Trifecta tune, you can log, and send it in with the info. Tell them how fast your speedo says when GPS tells you you're doing 65mph, or vice versa.

Yeah I knew that...totally knew that....

 

[laborsmith]

Trifecta can. In case there is any doubt.

Laborsmith

 

[Kuntryboy865]

Trifecta can. In case there is any doubt.

Laborsmith

For a fee right?

 

[Eric Smit]

for a free, if you have a premium tune.

 

[theenico]

If the tires you get/have are 24.9-25.1 inches tall, your speedo won't be off. The ideal size would be 205/55R16. That's the size that Sonics with the optional 16" wheels use.

 

[Kuntryboy865]

If the tires you get/have are 24.9-25.1 inches tall, your speedo won't be off. The ideal size would be 205/55R16. That's the size that Sonics with the optional 16" wheels use.

Yeah im running 205-55-16.

 

[SPOTWORK]

I'm running 225/30/19 and its pretty much bang on