Mutt

iTrader: (5)

Car Facts - 2004 Z Enthusiast 6MT. I am running 245/45/17 (17 x 8) on the front and 275/40/17 (17 x 9) on the rear. Problem - On some corners, even slight curves in the road, my tcs/vdc (not sure which it is) comes on and I lose power. In researching this I found some answers, but need more help. The following is from a post to which I have included the link to. It is regarding another forum member who has the same issue apparently.

It read, "Short story - your front tires are 0.7" taller than the rears. It needs to be reversed, the fronts need to be 0.5 to 0.75 shorter than the rears" (as found in this post... https://my350z.com/forum/maintenance...le-height.html

So should I be running like a 245/35/17 on the front? This seems impossible to find with a brand matching set of 275's in the rear, unless I go with Falken's FK-452's and stay with Goodyear Eagle F-1 All-Seasons in the rear. I would like to go with matching tires all around. I could go with Nitto NT450's 235/40/17 and 275/50/17's. Do you think this would help and be a good set-up? Any other ideas from anyone would be greatly appreciated!

And yes, I know I am only running 17 inch wheels, so please don't give me too much crap about that =). Thanks everyone...hope to hear from you all soon! Thanks!

davidv

iTrader: (2)

Front tires are taller than rear. 90 percent certain this is your problem.

DavesZ#3

iTrader: (26)

The 245/275 sizes work great when both have the same profile, i.e. 245/40 and 275/40 or 245/35 and 275/35. When you mix profiles (245/45 and 275/40) as you have, you can easily throw off TCS and/or VDC.

It's all explained here... https://my350z.com/forum/showthread....1&postcount=45

terrasmak

iTrader: (8)

255/40 up front. But actually you should be running taller tires

Mutt

iTrader: (5)

Thank you all so much for the responses so far! Much appreciated! Terrasmak, can you explain a little further why I should be running a taller tire? And any suggestions on brands if I do go taller?

ThE_JacO

Your tyres are staggered wrong, and probably of insufficient diameter in the back to begin with.
Stock on mine was 225/50 R17 in the front and 235/50 R17 in the back with re050, however (going by GPS vs car readings) it was still not 100% ideal (no vdc problems but considerable reading discrepancy as early as 40kph).

Now with 245/40 and 275/40 R18 fk452 readings are pretty much aligned with the GPS tic for tac up to 110-120, around that discrepancy starts creeping in a bit but it's normal. VDC also seems to kick in marginally less when I take driving lessons and do the run with it on, which makes me think that's pretty much the ideal diameter, but that wasn't really a problem before anyway, and it's very possible just the newer tyres are making that difference.

At 245/45 r17 you're pretty much bang on spec for the front, your back however is completely off. 265/45 r17 is as close to factory (and my absolutely irrelevant statistics of 2 samples ) as it gets for your setup, 275/45 r17 is still well within tolerance and shouldn't give you any trouble.

Leave your front alone and just get the right sidewall height for the back and you'll be good.

For the "what tyre" suggestion you can probably just search past threads, and come to the conclusion it's not the kind of question you want to ask without covering yourself in asbestos.
Everybody will basically tell you that whatever they're running on now is the best tyre in the world, and whatever the post above theirs was suggesting was exactly what they had before and is absolutely sh*t, and the above poster is a moron and a treehugger for using them (which incidentally made them a moron and a tree hugger until their previous batch got worn down, but that's beyond the point).
Search and fish for links and you'll be fine on that
The better answers you'll find are links to sites and pages

Mutt

iTrader: (5)

Thank you all for your help. Great learning experince!

Mutt

iTrader: (5)

Update...I ended up going keeping the 245/45/17 setup in front and went with a 285/40/17 in the rear. I could not find a 275/45/17 tire anywhere. No more tcs/vdc problems. Thanks to everyone for their help!

terrasmak

iTrader: (8)

Major understeer and crappy handling FTL

Spike100

^^ I agree. Mounting a 40mm stagger is way too much difference front to rear, especially with a higher sidewall tire required for 17” wheels. I would expect this setup to have excessive understeer.

--Spike

Mutt

iTrader: (5)

OUCH...hahahahahaha
I wouldn't say excessive understeer is the case. So instead of firing off an immediate and pi$$ed off reply (I must admit I wanted to ) I decided to go and test the car out a bit. I must say it is not bad at all. I don't pretend to know too much about the wheel/tire arena as this is quite new to me, which is why I do appreciate all the ideas/help. I am definitely not beyond learning, be it the easy or hard way. If it turns out that I do encounter some major/excessive understeer (I sure hope not) then I guess what they say is true...the best lesson learned is a lesson bought.
Although I am limited by the rims I have, I am still trying out different tire setups. Maybe one day I will step it up a notch and get a more "appropriate" set of rims for my Z, but I just can't seem to let go of what I got. I bought them off a friend who was running them on a 240sx. Anyhow, thanks again for all the comments and tips.

Just out of curiosity...so even though my new setup is wider in width and lower in sidewall height, overall height and circumference, and in turn has lower differences front to back (according to the dml tire and wheel calculator) than the factory 17" setup (225/50/17 and 235/50/17), I would still be prone to major/excessive understeer? Is it not so much what I just mentioned as it is about the front and rear sizes working in conjunction? Like I said, I am still learning, so please don't rip on me too hard...

terrasmak

iTrader: (8)

From the factory your has a 225 front and 235 rear in width , so you subtract 225 from 235 and you end up with 10. That is the difference in width from front to rear tire. The more of a difference there is , the more the car will push (understeer).

These cars like yours have a 10 mil difference and all the other with 18's and larger wheels have a 20mm stagger. I wouldn't go more than the 20mm stagger unless really needed 500hp etc etc but things like that are a different ball game.

Spike100

Mutt… No problem on your request for an answer with more refinement. The good question you present benefits from more discussion.

As terrasmak points out, the greater the width-stagger front-to-rear, the more under-steer you experience. That’s not to say understeer is a terrible thing since it can keep you safer in hard turns (you are less likely to rotate, which can be really bad).

In fact the Nismo wheel/tire setup uses a 30mm width stagger with 245 on the front and 275 on the back (obviously Nissan wants the car to understeer, and that is certainly for a safer drive). To put this into perspective, 10mm is only 0.39” (or saying it differently, 30mm is only a 1.25” difference).

Right now, I’m driving a 245 front and rear setup. I really like the neutral handling and its quick turn-in, but it can get tricky. For example: If you are on and uneven roadway (slippery due to sand/road debris, road cracks, etc.), the front might turn-in quickly, but the back could possibly “slide out.” Now, you’re in a rotating car, and the only way to save yourself (if VDC is OFF) is counter-steering.

I'm not trying to confuse the good issue you present, but instead providing other arguments and info.

--Spike

terrasmak

iTrader: (8)

Actually the NISMO has 265/35-19 rear tires that keep it at a 20mm difference.

Spike100

^^ I was referring to the Nismo aftermarket wheel/tire setup (tire width is 245 F and 275 R on either 18" or 19" Nismo wheels), and not the Nismo Model Z.

--Spike

Mutt

iTrader: (5)

I think I am starting wrap my head around this concept. terrasmak and Spike100, thank you very much for elaborating on this! So my setup is currently running a 1.57" difference in width stagger front to back, which is pushing the limit if Nissan/Nismo is running a 1.25" difference in width stagger, and they WANT it to understeer a bit (for safety purposes). Basically, Nissan/Nismo did the engineering and in their opinion found this (1.25") to be optimal, and I have gone slightly out of this realm and may experience more understeer than what Nissan/Nismo have deemed an allowable amount of understeer. That makes sense. I do appreciate all the help! Definitely a great learning experience here.

Spike100

^^ Thanks for the reply.

Not to add confusion… But, don’t get too hung-up on the under-steer tied to a “tread width paradigm.”

Nissan’s setups, 225 F with 245 R (a 20mm difference); or the aftermarket Nismo 245 F with 275 R (a 30mm difference) are examples that the front to rear width ratios also depend upon the tires’ width, and not just the ratio between front and rear widths.

If you mount a 245 tire on the front, you notice a significant difference in turn-in over the 225 tire. To maintain the same under-steer, Nissan’s Nismo setup goes from a 20mm difference to 30mm (and, that’s a huge difference in percentage comparing the different widths).

Looking at this differently:

• I have a Performance model and have the stock engine. That means I really do not need to go to 275’s on the rear since my engine cannot hardly overpower 245’s on the rear.
  
  
• However, I hate the under-steer and poor turn-in that I get with 225’s on the front.
  
  
• So, I went with 245/40-18” front with 245/45-18” rear. What a difference this setup makes! I have very fast and solid turn-in with almost neutral steering. The car handles just great (and much better than 225 F with 245 R). I only need to be careful not to push too hard in a turn since the neutral-steering is more prone to rear-slideout.

--Spike