I've read through more than a few threads (some humorous) about rear traction issues with the G37 in an attempt to gain a bit of insight and possible solutions.

My IPL has very little rear traction, under partial throttle no less, in the first three gears. Tires are the stock RE050A's and are most likely less than a year old as they're almost full tread depth and my car has 21K on the odometer. I believe the dealer swapped the tires out since it was under a maintenance plan with the first owner.

I've been experimenting with tire pressure and it's not really helped. I can roll out of a stop light and spin the tires up in first gear with less than half throttle. If I leave from a dead stop, full throttle, it'll spin excessively in three gears, no wheel hop, with the dash lighting up like a christmas tree. Pulling out into traffic, whether left or right, with medium throttle is an episode in steering wheel manipulation and controlling the tail with the VDC stepping in to keep things pointed in the right direction. The car needs to be pointed straight and rolling at a decent clip before squeezing the throttle full on. It sucks getting hammered on a left turn from a stoplight by a Prius that just stuffs me up the inside by two car lengths before I can get the car straight and hammer the throttle.

I make it sound worse than it really is and frankly, it's pretty fun most of the time. Still, I'd like more rear grip to take advantage of the HP and the gearing. The car is a blast and I'm really starting to bond with it (aka finding reasons to go out and drive).

I have a few theories about what's contributing to my rear traction issues. First, 19" rims with short, stiff sidewalls. Second, cool temps (50-75 degree temps as of late) and max performance summer tires. A stiff rear sway bar, bushing flex, and maybe even the stock Bridgestones may be contributing factors. Short gearing on the 7AT. Lastly, I think my alignment may be off in the rear. I've been reading quite a bit on one of the 370z forums and it seems rear toe can have a drastic effect on rear traction.

I'm going to swing by the dealer on Monday and have them check the alignment and also get a full inspection while I'm at it. I figure I'll start with the cheap stuff first and go from there. I'm not replacing what are almost new tires any time soon.

I'd be lying if I said I haven't considered a set of coil-overs with a very, very mild drop. I think I'm going to leave the sway bars stock since the car isn't headed to the track and a stiffer rear bar alone isn't going to help traction. From what I've read, I believe the stock spring rates are:
9.79kg/mm front
8.05kg/mm rear

I'm looking at the Bilstein PSS's or even perhaps a set of Aragostas as that's what I ran on my 3rd gen RX7 for some time and absolutely loved them. I learned what throttle modulation was on that car. Not easy in a 2500lbs, 500rwhp missile with no traction control. Bulletproof has a set of Aragosta S shocks with a slightly higher spring rate than what I currently have and I could, theoretically dial out some of the understeer with these as opposed to going with different sway bars. I'd go with KW V3's but it's too difficult to make quick adjustments to the rear shocks. I also don't want to significantly increase NVH. I've driven quite a few 370z's and even the touring model is quite an increase over the IPL.

Not sure where else to look in terms of improving rear traction. I feel like the car is slightly under-tired. I don't want to change the tire diameter or add a ton of rotating weight. I'll switch to a set of Michelin PSS's when the time comes as they seem to be a nice improvement of the RE050A's. But like I said, the easy and cheap stuff first. I'll report back periodically with updates as I check things over or make changes. It's a small issue but hey, it's my issue and I need to keep my mind off of making any and all changes to the powertrain as I'm a recovering power addict and am going on my sixth year of said recovery.

 

Also possibly looking at these once I have my alignment checked. If it's within spec, I may be getting lots of bushing deflection. I know these would increase my NVH a bit but might be worth it and they're relatively inexpensive.
Adjustable Rear Traction Arms for the 370Z and G37 | SPL Parts

 

Performance summer tires and cool temps are probably the single biggest reason for low grip. Also, check the DOT number on the tire sidewall to determine the date of manufacture. As tires age the compound hardens resulting is less grip.

An alignment check would also be a good idea.
Sway bars have no effect on straight line traction.

 

Will check DOT number before heading out to the office today. I know from my track days with cars and motorcycles, a 20 degree temp change has a dramatic effect on tires. Wasn't sure what the optimal temp range was for a DOT-type summer performance tire but assumed anything in the 60-75 degree range wouldn't cause that much of a dramatic drop. Maybe they've just gotten that "specific".

 

Get rid of the RE050 tires. Potenza S-04 or Michelin Pilot Sports will go a long way to help your traction problem. I'm running the Potenzas on my S sedan and they made a significant difference. Better grip, softer and quieter to boot.

 

Last two digits on the tires are 12 so assuming they're 2012's but weren't put on til late in 2015 based on current tread wear and miles on the car (21K). If it does turn out to be the tires and the alignment is fine, I'm just going to have to live with it for a bit and swap them out in the fall or next spring. May try the SPL traction bars too just for sh*ts and giggles.

 

Seems like a fine plan

 

My 2010 Sport has horrible traction. Had 60% tread on hankook v12's when I bought the car used. After a year and a half needed tires. Put some inexpensive 245/275 tires on thinking they would improve traction. NOPE!!! I'm gonna suck it up till the end of the year and get some khumo's, Bridgestone, yokos, G-Max or whatever I can find cheap.

 

I should probably start a new thread on this one but has anyone with the staggered wheel setup run a 235/40/19 up front? Specifically the Pilot Super Sports.. It's half an inch smaller in diameter up front, ever so slightly wider and thinking it'll reduce the propensity to understeer without making any changes to the rest of the suspension.

Specs. The slight drop in diameter up front may make turn in a hair sharper with more feedback under load and will help loose some of the reverse rake look happening with the stock wheels/suspension.

After a month of really examining the handling, I think the car needs just a bit more front end grip, a hair more rebound damping and possibly a bit more sway bar in the front along with solid bushing traction bars and stickier tires in the rear. Ok maybe a sliver of high speed compression damping but not much...I feel like the spring rates are decent and you could probably get away leaving the stock sways alone with a bump in spring rate.

I really don't want to increase the rotating mass of the tire but looking at the spec on Tirerack, the PSS's will loose several pounds of rotating mass even when upsizing the tires. I'm not 100% sold on 20mm spacers in front due to the increase in steering sensitivity. I may end up going down to 15's or even 10mm with wider front rubber.

I used to run 285's all around on my RX and it really made it easier to dial in other components. Just better balanced overall.

 

If you think you suffer understeer, a larger front bar will make it worse.

 

True. Slightly stiffer springs front and rear may be the way to go along with slightly wider rubber up front. I'm thinking the IPL bars are big enough for street duty.

 

I had similar rear traction issues when I first got my IPL. It was kinda fun at first being able to goose the throttle and feel the rear shimmy around. But I was planning my next Dragon run and decided a squirrelly rear end is not a good mix for mountain roads. After a lot of research, I tried Pilot Super Sports on the rear using stock sizes. I haven't noticed any twitchiness since then.

 

There are some that have the theory that increasing offset (via wheel spacers or with actual wheels) reduces the spring response; increased leverage (wheel further out) making it easier to compress the spring, and resulting in less rear wheel hop.

Come to think of it, I cannot remember the last time I had problems hooking up at launch. I do break loose some when I want to. But I am running Pilot SS in the summer and Pilot Sport AS 3 in the winter.
I am running wheel spacers front and rear (different sizes depending upon which tires I am running. I am also lowered

 

I just added spacers not too long ago with no change in traction. I never seem to get wheel hop, the tires just spin which makes the loss of traction at least manageable. I keep wavering on making other changes just to see if it'll help, LOL. It'd be nice if a set of PSS solved all the ills.

Out of curiosity, anyone ever run four rear IPL rims all around? I think the offset would work, especially with the right spacers. One could theoretically run the 245's at all four corners that way.