Whats good y'all? I've had my 2013 G37x sedan 7at for 3 years and love almost everything about it. I have been wanting to mod the car since I bought it and will soon be putting some love into her. Today I drove my buddies 2010 G37x 7at. The only difference between our cars is that he has the 18" Duckfeet Enkei rims and I have the stock 5 spoke design 17" rims. And let me tell you, his car feels so much better in handling. It feels lighter, more nimble, but it even fixes a problem I've been facing with my 7at?! You see, my car in gears 3-4 wants to be shifted at about 2-2.5krpm, if you let off the gas higher (4k+) my motor will start engine-braking kinda hard (slowing me down fast) vs my buddies car that will roll through 3rd-4th no problem, I can bring his car almost up to red line smoothly / let off and it would still coast / feel better than mine letting off at like 4k in either of those gears. At this point we both think it is because of the wheels but don't understand how the wheels could effect something like how the gears feel... rotational mass maybe?? If I change to new wheels and it still feels like that I'd be so sad.

At this point I'm in the market for for some nice light weight wheels to see if this will fix the issue I always blamed the 7at for, still deciding between 18 or 19". Any input would be appreciated. I'm currently all stock but would like to get sway bars, CBE, tune soon and coils / bushings later. So I do want a rim/tire combo that will be aggressive but fit my car well for DD. I'm sure it will stay stock height for a while but need wheels ASAP! Looking for light strong wheels under 20lbs each (ideally). Thinking rpf1, duckfeet, 19" Coupe sport 10 spoke, NT03+M, etc. also id say $1200 budget with tires. If you know anyone selling send them my way! Also please recommend some wheel set ups that you think will run well with my car, I was leaning towards 18x9-10 all around. But I have to look into what fits best. I will try to find some pictures of the stance I am going for.

 

 

18x10.5 F & R WOW! Is this functional??



19x9.5 F
19x10.5 R

I like the meaty look on both of these. I'd imagine the wider tires makes for better handling?

 

So today I was driving home and decided to take my traction control off. I did this and my problem with the tanny went away... I could wind through the gears much more freely. I put the traction on n off a few times and every time I would put traction on it would start putting a lot more stress on my motor and slowing me down. Does that make any sense?

 

Bigger rims will rotate at a slower rate and, while you may feel like it's smoother, you'll actually be accelerating slightly slower. Is your friends' car modded or tuned at all? Could also affect the 'feel'.

I'm kinda having a hard time following the testing. You let off at 4k+ and the car started engine braking? Were you in DS, D, shifting yourself? What was the position of the accelerator pedal? Seems like you did a half pull in your car and a full pull in your friend's car. Of course your car is going to start engine braking pending throttle position, It's holding the RPMs waiting for you to get back on it vs. shifting into the next gear. All that is based on your history of throttle inputs; you know our cars come with ECU learning right?

The 7AT is also...odd. 1-2 are super short while 3rd is normal. 4-7 are as long as the yellow brick road. It makes for a very jerky and unpredictable ride. For what it's worth, my car is tuned, grounding kit, and I have 18 x 9.75 rims with 40/255 tires and the transmission still shifts as smooth as broken glass. I still think rims, rubber and a drop is mandatory for those with 17'' rims; the 4x4 ride height looks awful from factory.

 

Strange to see an old pic of my car randomly in someone else's thread.

OP, I wouldn't look to the difference between your 17" wheels and your buddy's 18" duckfeet as the source of whatever you were feeling. Particularly to how the drivetrain behaves between the two cars. That doesn't make any sense.


That's why tires on larger wheels have a more narrow sidewall.


And there it is.

 

My friends car isn't tuned or modded at all (neither is mine). Only difference is the rims / tires.

For what was happening I was talking about in Manual mode through DS (as this allows me to "roll the gears out"), where the gears don't change unless you change them. If I let off the gas @ even 3k+ in 3rd with like 20-30% throttle it would cut the power instantly and slow me down to almost a stop. It felt like 2nd almost (but slightly taller). 4th gear felt like this also, like they were rlly getting cut off after 3kprm. As I said though, last night I turned traction off and it literally fixed the issue... Even when I have traction on now the issue feels less profound. I will try to take videos of this to show my insanity. I drove the car a good amount today (98% with traction off) and it felt really good rolling through the gears. Made me all giggly.

How did the tune effect your shifting / 7at? Ecutek? Is the grounding kit worth it? *spoiler alert* I just placed an order for a Fast Intentions CBE today as I seem to have fixed the issue with my tranny!?!? So rims / tires / cai / coils / sway bar n bushings r gonna have to wait a lil bit, unless I come up on a incredible deal. I think I've settles on wanting 18x10.5 all around. Do you think this will rub / scrub at all with stock or coils?

 

LOLLLLLL which car was yours?

 

The white sedan with duckfeet. That pic is probably 7 years old.

 

About the same. There's not a whole lot that can be done from a tuning perspective ( I asked specifically). I was tuned with UpRev -- Tuner tweaked the table so tip in was a bit more sensitive. Driving aggressively / moderately the transmission behaves normally for the most part and is responsive. If I go from driving lazy to all of a sudden asking the car to perform then it can be a dog sometimes and that infamous delay is there. All depends on my speed. If I'm already moving at say 40mph and I ask the car to get me to 60mph in a hurry then the delay isn't too bad but if I'm coasting at say 15-20 mph then the car definitely has a hard time getting into the correct gear.

IMO, the grounding kit is worth it. Some say it's a waste but I actually installed one within the first 2-3 days of ownership and drove the car with it on for a quite awhile. Safe to say, I only knew the car with the grounding kit. I took it off during a throttle body cleaning to see if it made a difference and my car was noticeably more laggy and less responsive.

18x10.5 won't rub. I ran a 40mm side wall on coils and will be bumping up to a 45mm sidewall (hopefully) soon. I have more than enough room.