Red Raspberry

Anyone gone with a larger than stock diameter tire? Say front and back an 1" taller?

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2010 Red 2.0L track

Kolk1

1inch taller, and your ABS/Traction control is going to hate you.

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Red Raspberry

Even if it's one inch on both front and back? Same ratio front to rear.

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2010 Red 2.0L track

2.0TGT

you wont have any problems as long as you maintain the front to rear height ratio

Red Raspberry

How much can you wander from the stock ratio?

Here's some numbers. I would rather go to the wider than stock tires but definitely want taller tires.

Rear height
245/45/18= 26.7” stock
245/50/18= 27.7
275/45/18= 27.8”

Front height
225/45/18= 25.9” stock
225/50/18= 26.9”
245/45/18= 26.7

Stock rear to front height ratio – 1.030
245 50 / 225 50 ratio 1.029
275 45 / 245 45 ratio 1.040

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2010 Red 2.0L track

dunni88

I might eventually do this. I have 19" track wheels with stock tires on my Grand touring. I am betting that getting a taller tire in the rear is going to help me get better gas mileage, but probably only 1mpg.

I might be interested in going to something crazy like 245/50/19 in the rear. Anyone messed around with something like that?

I'm pretty jealous of the V6 Mustangs that are able to squeeze 30+mpg on the highway, I'd assume they do it by revving at ~1800RPM and not the ~2300RPM we run at with our V6.

Alt0id

Keep in mind there is a point that two low of rpm on a particular engine can be less fuel efficient, if in order to maintain speed opposing the wind resistance creates enough load on the engine to lug it. No idea the science behind it, but I'd assume our engines, coupled with the gearing is close to the most efficient possible, given that Hyundai has a vested interest in higher fuel efficiency.

Thats my understanding anyhow, but I'll discuss with my brother who is an engineer, and see if I have it right or just speaking out of my ass

ControlFreak

The traction control shouldn't care if the ratio is maintained but since the ESC would see a lower speed input than what you're actually doing I would suspect that the stability control would be affected since road speed is one of the factors it uses to decide how soon and how much to intervene in any given situation.

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2010 Nord Grey 2.0T
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PwrAxel

Snoopy0812

You're not talking out your ass. Too low of an RPM and the engine is constantly increasing fuel to generate enough torque to overcome the forces applied to it (wheels vs. road, aerodynamics vs. speed). Cruising down the highway you're not actually requiring that much power, but say you're trying to record a top speed, when you become drag limited its when you don't generate enough power to overcome the resistances. The GC is mostly gear limited however.

Stability control uses individual wheel speed sensors. When a driven wheel overcomes the speed of the trailing wheels it's detected as slip. Narrowing the differential allows the TCS to engage much more easily.

Upsizing the rolling diameter will affect your speedo and RPM, both of which are taken from the CKPS sensor not the wheel speed sensors.

Red you'll be going into relatively unknown territory because I can't say for certain or not how much CKPS input is checked against wheel speed sensors.

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ControlFreak

So you're saying Snoopy that road speed is not read directly anywhere but is a calculated value based on engine rpm and what gear you're in at the time?? Theoretically I guess that's possible with the auto but a manual? If you were slipping the clutch your speedo would be jumping up quickly with the rpms but your actual road speed would be very obviously much lower (somebody surely would have commented on that by now).

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2010 Nord Grey 2.0T
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PwrAxel

Snoopy0812

Ever noticed how when you spin out on ice your speedo goes up with your rpm if you have the TCS off but you're not actually going any faster? If it was based on the wheel it would have to be on the driven wheel and the auto maker would have to be assured that the wheel that was slipping was the one with the sensor on it, every time you went around a corner the inside wheel travels less distance than the outside wheel, before computers it would be impossible to correct for corners.

It's been done this way for years and years, it's why larger wheels or worn out tires f*ck up your readings, it's why Ford started putting correctables in their ECU tables, switch to 20's? Take the car in, input your new tire size into the ECU and your speedo is now correct'ish.

edit:
we actually have a thread already on how the speed is calculated on the coupe. Don't remember what it's called though, had something to do with the ZF because the TCU for the ZF actually knows and reacts based on the speed, not just the wheel channels.

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pwned88

Actually I've noticed the coupe is the first car I've owned that doesn't. I'm guessing it must calculate off the front wheels during spin cause mine reads actual speed. It threw me off cause I used to watch wheelspin in my non TCS vehicles by a sudden increase on the speedo.

sent from my not-so-smartphone

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boostedpse

I run 255/40 19 on the rear with stock size fronts (traction is much better). I can say that there have been a few times when I abused the car with tcs on that it went into limp mode. Also, TCS doesn't feel as "helpful" or responsive as it did on stock sizes. I almost always drive with it off for those reasons. I have never considered my rear tire size as being the culprit, but I guess it is possible.

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Snoopy0812

It's compensating, it's not calculated by the wheels.
I'm even willing to provide evidence to my statements.


1. Cluster assembly 2. Seat belt switch
3. Vehicle speed sensor 4. Engine coolant temperature sender
5. Oil pressure switch 6. Brake fluid level warning switch
7. Parking brake switch 8. Door switch
9. Fuel gauge sender 10. Wheel speed sensor
11. ABS ECU

Can be found here on HMA; GENESIS COUPE(BK) >2010 > G 2.0 T-MPI > Body Electrical System > Indicators And Gauges > Components and Components Location

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pwned88

Compensating is the word I meant to use. This car is the first one I've ever owned that showed actual speed during wheel spin

sent from my not-so-smartphone

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Red Raspberry

That's very near the ratio r/f that the 18s are.

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2010 Red 2.0L track

ControlFreak

Well after some exhaustive research I can say I've determined a few things for sure but a definitive answer to this question does not exist online right now. Here's what I do know:

1/ The crankshaft position sensor (CKPS) and the vehicle speed sensor (VSS) are two entirely different animals.
2/ The CKPS is an input to the ECU ,or ECM as Hyundai likes to call it,(obviously) and the VSS is a direct input to the BCM. As shown here:






3/ Comparing Snoopy's picture above to this one it is clear they are not located in the same areas of the car.





4/ From what I read online Hyundai historically likes to place it's VSS's on the transmission or on the right front wheel ,it seems to vary from model to model and even sometimes from auto and manual cars of the same model. There is no definitive answer as to it's exact location on the gencoupe online right now.
5/ The CKPS part # is 39180-2C500 , the VSS obviously has a different number but I was unable to find it online, perhaps someone who has access to Hyundai parts # listings on here can find it for us.

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2010 Nord Grey 2.0T
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PwrAxel

Red Raspberry

Looks to me like the wheel sensors go to the ESC module then out to the instrument cluster on the Can Bus. The ECU gets a RR speed signal input from the ESC module.

Out of the instrument cluster comes a processed signal that feeds an input signal to the AC control module, BCM, audio, auto lamp leveling device and the data link connector.

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2010 Red 2.0L track