Tire Size help pls

osbornsm · 07-16-2016, 01:44 PM

I need to replace my front tires.
I'm looking @ 255/40/19 for the front.

I have 305/30/19 on the rear of the Z.

QUESTION:
- Should I buy 255/35 or 255/40 for the fronts?
- Wheel is 9.5 wide

Thank you kindly!

barncobob · 07-16-2016, 02:17 PM

Id go to TireRack, pick appropriate tie U want go to "SPECS" and it will tell U everything including diamaters of rims acceptable,,,height tire, weight, etc.

hjo1078 · 07-16-2016, 03:38 PM

Quote:

Originally Posted by osbornsm

I need to replace my front tires.
I'm looking @ 255/40/19 for the front.

I have 305/30/19 on the rear of the Z.

QUESTION:
- Should I buy 255/35 or 255/40 for the fronts?
- Wheel is 9.5 wide

Thank you kindly!

you can go either 255/35 or 265/35, i wouldnt do the 255/40 sidewall, thats going to mess with the rolling diameters, you would have a 27.4'' rolling diameter front with a 26.3'' rear

osbornsm · 07-16-2016, 08:17 PM

Quote:

Originally Posted by hjo1078

you can go either 255/35 or 265/35, i wouldnt do the 255/40 sidewall, thats going to mess with the rolling diameters, you would have a 27.4'' rolling diameter front with a 26.3'' rear

Well crap, I have new 255/40 in the garage currently. Just delivered. :/

Would it cause a problemo?

hjo1078 · 07-16-2016, 08:21 PM

Im pretty sure its going to trigger some lights on your dash. But i could be wrong. Im also running 255/40 on my wheels but i matched the rears up w 305/35/19. That way the rolling diameter stays pretty close. I did notice w these sizes the speedometer became way more accurate.

Sent from my iPhone using Tapatalk

osbornsm · 07-16-2016, 08:27 PM

Quote:

Originally Posted by hjo1078

Im pretty sure its going to trigger some lights on your dash. But i could be wrong. Im also running 255/40 on my wheels but i matched the rears up w 305/35/19. That way the rolling diameter stays pretty close. I did notice w these sizes the speedometer became way more accurate.

Sent from my iPhone using Tapatalk

Tire rack says: 27.1 vs. 26.3 rear diameter.
Hmm... Curious.

ChaseZ · 07-16-2016, 08:28 PM

255/40 is 27"
255/35 is 26"
305/30 is 26.2"

if you already have 40's for the fronts, you could always replace your rears with a taller tire too.

325/30 will get you up to 26.7" (which is oem tire height for 370z) and within 1/4" of those 40 fronts. Just some extra food for thought.

barncobob · 07-16-2016, 09:07 PM

my thinking is if the car isn't 4WD/AWD the front vs. rear diameters don't matter

jchammond · 07-16-2016, 11:20 PM

265/35 or 255/35 if you want a bit of rake....max diameter differential is 3%

BGTV8 · 07-17-2016, 04:19 PM

Quote:

Originally Posted by barncobob

my thinking is if the car isn't 4WD/AWD the front vs. rear diameters don't matter

The VDC system expected same OD (within ~20mm OD).

If tyre diameters are mis-matched and outside the VDC system tolerance, it pops the slip light on the dash because it "thinks" that tyres on one axle are rotating faster than the other and it wants to intervene.

There is no precise figure for the tolerance, but generally accepted to be around 20mm (0.8-inch).

Rusty · 07-17-2016, 11:34 PM

Quote:

Originally Posted by BGTV8

The VDC system expected same OD (within ~20mm OD).

If tyre diameters are mis-matched and outside the VDC system tolerance, it pops the slip light on the dash because it "thinks" that tyres on one axle are rotating faster than the other and it wants to intervene.

There is no precise figure for the tolerance, but generally accepted to be around 20mm (0.8-inch).

07-16-2016, 01:44 PM	#1 (permalink)
osbornsm A True Z Fanatic Join Date: Jun 2011 Location: WHAT Posts: 2,551 Drives: 2018 Camaro SS 1LE Rep Power: 424	Tire Size help pls I need to replace my front tires. I'm looking @ 255/40/19 for the front. I have 305/30/19 on the rear of the Z. QUESTION: - Should I buy 255/35 or 255/40 for the fronts? - Wheel is 9.5 wide Thank you kindly! __________________ 2018 Camaro SS 1LE (455hp) - 2011 Nissan 370z (333hp) - 2004 VW R32 (240hp) - 2000 Civic Si (160hp)

07-16-2016, 08:28 PM	#7 (permalink)
ChaseZ A True Z Fanatic Join Date: May 2016 Location: Calgary Posts: 3,799 Drives: 16 370z Rep Power: 94683	255/40 is 27" 255/35 is 26" 305/30 is 26.2" if you already have 40's for the fronts, you could always replace your rears with a taller tire too. 325/30 will get you up to 26.7" (which is oem tire height for 370z) and within 1/4" of those 40 fronts. Just some extra food for thought. osbornsm likes this.

07-16-2016, 09:07 PM	#8 (permalink)
barncobob A True Z Fanatic Join Date: Sep 2015 Location: hangtown, CA Posts: 1,164 Drives: 16 370Z auto Rep Power: 590	my thinking is if the car isn't 4WD/AWD the front vs. rear diameters don't matter charjohnnie likes this.

07-16-2016, 11:20 PM	#9 (permalink)
jchammond A True Z Fanatic Join Date: Nov 2014 Location: South Carolina Age: 58 Posts: 15,204 Drives: 13’ 370Z TS 7A/T Rep Power: 2684395	265/35 or 255/35 if you want a bit of rake....max diameter differential is 3% BGTV8 likes this. __________________ MazWorx built long block \| FI-TT-100 Stage 2.75 \| IPT built 7A/T http://www.the370z.com/members-370z-...s-musings.html

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07-16-2016, 02:17 PM	#2 (permalink)
barncobob A True Z Fanatic Join Date: Sep 2015 Location: hangtown, CA Posts: 1,164 Drives: 16 370Z auto Rep Power: 590	Id go to TireRack, pick appropriate tie U want go to "SPECS" and it will tell U everything including diamaters of rims acceptable,,,height tire, weight, etc.

07-16-2016, 08:21 PM	#5 (permalink)
hjo1078 Track Member Join Date: May 2011 Location: virginia Age: 46 Posts: 572 Drives: twin turbo 370z Rep Power: 5395	Im pretty sure its going to trigger some lights on your dash. But i could be wrong. Im also running 255/40 on my wheels but i matched the rears up w 305/35/19. That way the rolling diameter stays pretty close. I did notice w these sizes the speedometer became way more accurate. Sent from my iPhone using Tapatalk