Changing wheels/tires affect speedo?

**Darren** · 01-29-2013, 01:29 AM

Will going from 245/45/R19 (stock) to 275/40/R18 in the rear affect the speedo/odometer?

If so, is that something a dealer could change real quick or would that cost me :(

**PaxtonShelby** · 01-29-2013, 01:58 AM

245/45/19 = 86.962 circumference and 27.681 height

275/40/18 = 83.758 circumference and 26.661 height

circumference difference = 3.204 inches, which equals a 3.68% decrease, which will make your speedo read that much FASTER

height difference = 1.02 inches, which will give you a 0.51 increase in the space between the top of the tire and your wheel opening

It is late and I'm tired...but I think the math is right...

I used http://www.csgnetwork.com/tiresizescalc.html

You looking at 2007-2009 GT500 wheels/tires Darren??

**crusher101** · 01-29-2013, 02:51 AM

Tuner can fix the problem while making the car faster ;)

**Darren** · 01-29-2013, 01:45 PM

not gt500 wheels, i actually just bought a set of AMR wheels. Got a great deal on them and they are the charcoal color which matches my car really well. so 255 up front with 275 in rear. And afterwards i plan to lower the car so itll have a really nice stance

I got some plans for my car and i'm gonna post pictures once the weather allows

**03 OW SVT** · 01-29-2013, 04:36 PM

The AMR Drifts?

**Darren** · 01-29-2013, 06:09 PM

http://www.americanmuscle.com/charco...tomo-stag.html

yup, these wheels

**03 OW SVT** · 01-29-2013, 07:06 PM

Those will look awesome Darren

**PaxtonShelby** · 01-29-2013, 07:09 PM

Very nice! Any reason you don't want to go with 19's? I didn't read all the specs - I guess they'll clear the Brembos you're going to install?

Have you decided what strut/spring combo you are going to go with when you lower the car?

**Darren** · 01-29-2013, 08:11 PM

well, the 19s were obviously more expensive. i'm a college student with an expensive car hobby

But the other main reason was because tires are much cheaper.

im planning to buy SR Springs from AM. drop 1.5" on all 4 corners. I will probably stay stock strut/shocks for now. Once the summer hits and can drive her more ill make a decision then.

and yes the 18's will clear the brembos :)

**PaxtonShelby** · 01-29-2013, 10:06 PM

If you drop it more than 1 inch there is a chance you will need an adjustable panhard bar. I have heard really good things about Koni STR.T struts used with Steeda Sport springs. If you change springs that drop the car over an inch but do not upgrade the struts and shocks at the same time I have heard that the ride and handling can suffer. I hear ya on the expensive hobby thing - seems like we have to hit the lottery to pay for these cars let alone mod them a little.

Waiting for my car is driving me nuts, so it is nice to see you and the other SMG GT on here working on some mods!

**Darren** · 01-29-2013, 10:29 PM

Thanks Paxton i will definitely have to research those before i do anything! I know tho i want to lower the car asap because the 4x4 look with the smaller 18s will drive me insane.

I like the green, grabber blue etc but im with you SMG is honestly the best color in my opinion! Im glad you ordered your 14 that way!

**PaxtonShelby** · 01-30-2013, 08:55 AM

Best price I have seen is $365 shipped for the Koni STR.T struts/shocks. The Steeda Sport springs are around $270. Then you need the 2010 ( I think ) GT500 strut mounts. That combo lowers the car 1" in front and 1.25" in the rear and reallly improves the handling. It also eliminates the pretty bad nose dive on the stock cars - like you get under hard braking or between gears when you're really getting on it.

There is a lot of great info on these cars over at www.themustangsource.com - check it out when you have a chance

I hear ya on the SMG. It is hands down my favorite. I guess we all think our "kids" are the best. :D

**Darren** · 02-01-2013, 02:56 PM

Thanks for the info! I really appreciate it Paxton! After a few paychecks I will definitely have my car down to Wolfpack for some fun

First on my list is suspension, nothing better than a mustang with good stance. Next is exhaust (want boss side exhaust sooo bad)

I kno exactly what you mean, a car is the most expensive thing I've ever bought so i treat it like a kid. My dad ordered a 2005 Mineral Gray GT when they first came out and it'll stay in the family forever. I was about 12 then and ever since i've always wanted that color or close to it!