Newbie question about wheels
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Joined: Jan 2014
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Newbie question about wheels
Hi Guys,
I have browsed this board for a while, as I just think that the G37 is just such a sexy car. My goal is to buy one in the near future, but as with many purchases, I wanted to read up on it before hand. Many roads lead me to this site, and I've made is a "home" for my information of sorts
In reading about rims/wheels, I noticed that a number of members ask things like "Oh, are those +25 all the way around?", or "What offset are you using?".
What does that mean? In my mind, I would just go out and buy bigger rims, put them on and it's done.... (I should say now, if it's not evident already I know very little about cars).
Also, question #2: when you put on aftermarket rims, are they usually bigger than the 19" that come on the car? If so, does it throw off your speedometer that much to the point where you need to "re-calibrate" the speedometer?
Sorry for the silly questions, but these have bothered me for a while now and I thought "why don't I just ask them?"
I have browsed this board for a while, as I just think that the G37 is just such a sexy car. My goal is to buy one in the near future, but as with many purchases, I wanted to read up on it before hand. Many roads lead me to this site, and I've made is a "home" for my information of sorts
In reading about rims/wheels, I noticed that a number of members ask things like "Oh, are those +25 all the way around?", or "What offset are you using?".
What does that mean? In my mind, I would just go out and buy bigger rims, put them on and it's done.... (I should say now, if it's not evident already I know very little about cars).
Also, question #2: when you put on aftermarket rims, are they usually bigger than the 19" that come on the car? If so, does it throw off your speedometer that much to the point where you need to "re-calibrate" the speedometer?
Sorry for the silly questions, but these have bothered me for a while now and I thought "why don't I just ask them?"
Thread Starter
Registered User
Joined: Jan 2014
Posts: 3
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Well I suppose I should have been very specific if I didn't want a smart-*** response.... (Google also knows that too )https://www.google.ca/?gws_rd=cr&ei=...on+of+smartass
In your experience, do you always recalibrate your speedometer? Or have some/most/none of you just learned that 50 on the speedometer really means 65 (for example).
)https://www.google.ca/?gws_rd=cr&ei=...on+of+smartassIn your experience, do you always recalibrate your speedometer? Or have some/most/none of you just learned that 50 on the speedometer really means 65 (for example).
Registered User
Joined: Nov 2013
Posts: 45
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From: Houston
Well I suppose I should have been very specific if I didn't want a smart-*** response.... (Google also knows that too )https://www.google.ca/?gws_rd=cr&ei=...on+of+smartass
In your experience, do you always recalibrate your speedometer? Or have some/most/none of you just learned that 50 on the speedometer really means 65 (for example).
)https://www.google.ca/?gws_rd=cr&ei=...on+of+smartassIn your experience, do you always recalibrate your speedometer? Or have some/most/none of you just learned that 50 on the speedometer really means 65 (for example).
Welcome to the site, hopefully you'll have good luck locating a clean new G for your garage 
As far as wheels, first it depends on what G you end up with. If you go w/ an AWD X model outside diameter of new tires is extremely critical (it's important w/ any model G, but especially AWDs).
Also if you have an S model G sedan or coupe or an XS Coupe you'll have much bigger brake calipers that will have to be considered when shopping for new wheels, many wheels won't clear the bigger brakes.
Offset is also a big consideration, this determines how much the wheel goes out from the hub, the more positive the offset is the further the wheel will sink into the fender, so for example a wheel w/ a +20 offset will stick out 25mm more than a wheel w/ a +45 offset. It takes a bit of playing w/ the numbers to see how this works. The coupe has a wider stance so they have more room for offset than a sedan. Typical aftermarket setups for coupes have offsets in the mid +20s, Sedans require a more conservative offset (tires sunken further into the fenders) so similar setups for Sedans would be in the mid +30s to mid +40s.
Here's a good calculator, and for a RWD 3% diameter difference is acceptable and 1% or less for AWD. Obviously as close to zero is always best regardless.
https://www.myg37.com/forums/tire_rim_calculator.php
When you get your G and need more help w/ tires/wheels just post in this folder~
Wheels & Tires - MyG37
As far as wheels, first it depends on what G you end up with. If you go w/ an AWD X model outside diameter of new tires is extremely critical (it's important w/ any model G, but especially AWDs).
Also if you have an S model G sedan or coupe or an XS Coupe you'll have much bigger brake calipers that will have to be considered when shopping for new wheels, many wheels won't clear the bigger brakes.
Offset is also a big consideration, this determines how much the wheel goes out from the hub, the more positive the offset is the further the wheel will sink into the fender, so for example a wheel w/ a +20 offset will stick out 25mm more than a wheel w/ a +45 offset. It takes a bit of playing w/ the numbers to see how this works. The coupe has a wider stance so they have more room for offset than a sedan. Typical aftermarket setups for coupes have offsets in the mid +20s, Sedans require a more conservative offset (tires sunken further into the fenders) so similar setups for Sedans would be in the mid +30s to mid +40s.
Here's a good calculator, and for a RWD 3% diameter difference is acceptable and 1% or less for AWD. Obviously as close to zero is always best regardless.
https://www.myg37.com/forums/tire_rim_calculator.php
When you get your G and need more help w/ tires/wheels just post in this folder~
Wheels & Tires - MyG37
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