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Saturday, April 25, 2015

Can I Run Different Sized Tires on My Nissan Skyline GT-R?

importavehicle.com NISMO R32 GT-R with R34 GT-R Wheels. 18 x 9 +30  245/40/18 Toyo R888

Can I Run Different Sized Tires on My Nissan Skyline GT-R?

A: A Nissan Skyline GT-R came with the same sized wheel and tire front to rear.

  Stock wheels and tire sizes
R32                 16 x 8 +30  225/50/16
R32 Vspec      17 x 8 +30 225/50/17
R32 Vspec II  17 x 8 +30 245/45/17

R33  17 x 9 +30  245/45/17

R34   18 x9 +30 245/40/18


The ATTESA, or all wheel drive system in a GT-R, uses inputs from the throttle, from the G-sensor, and from the ABS/wheel speed sensors to lock up the center differential.  If the wheel heights are different, they rotate at different speeds. The ATTESA/ABS ECU sees this as slippage. This causes lockup of the center diff. That constant lockup can lead to heat, slippage, and burning out the transfer case clutch pack.

ATTESA System overview technical document

So, can you do it?  The answer I like to give people is - NO.  The reason is because I don't want them to do something wrong, and screw up their transfer case or ATTESA system, and blame it on me.

The real answer is, if the overall heights/diameters are similar enough, you can get away with different sized front and rear wheels, tires, etc.

There are no specs in the R32 Service manual, but the R35 service manual says

Diameter difference front/rear
0-4 mm STOCK
4-8 mm OK
8mm- and greater NO GOOD

I have seen worn tires throw an ATTESA code. You could get a code running tire pressures way wacky ie 40 psi in 3 tires, and 20 psi in one.

Most often people try and do some kind of staggered setup, don't do the calculations before they purchase tires, and now end up with a 2wd Nissan Skyline GT-R.  Which may sound like fun, until you want/need the all wheel drive.   So always check the diameters, make sure before you buy anything.  The safe way is stay square. Lets you rotate the wheels and tires around the car. Great for real cars that run on the race track, and even street car guys that run some miles.



Tire Rack Calculating tire dimensions



If you are looking for R35 Nissan GT-R information on the same subject - check out - Nissan GT-R Wheel and Tire Fitment at 2009gtr.com



R32/R33 transfer case

Transfer case internals. Clutch pack, front drive, and chain
R32 ATTESA Codes
R34 ATTESA Codes


Buy USA Legal R32 Skylines at Importavehicle.com!
Buy-R.com for Nissan Skyline GT-R and GT-R parts.

NISMO option wheels. 16 x 8 +30. 255/50/16 Mickey Thompson ET Street Radials


4 comments:

Anonymous said...

Hi!
Are we sure the oem tires of standard GT-R BNR32s were 205 50 16? Isn't it 225 50 16??

Sean Morris said...

They were 225/50/16. Corrected. Thanks for noticing.

Anonymous said...

With respect to my '99 R34 GT-R V-Spec, I'd like to run an 18x10 +20 with 265/35/18 tires. Am I in the safe zone with this? Based on the R35 Service Manual that was mentioned in the R34 wheel/tire blog, it appears I might be close. What are your thoughts on this? Thank you in advance for your reply.

David Dunn said...

I have a 97 R33 Vspec with 265-35r18 mounted on 18x10.5 Advan T-5 but I have not had the time to remove them to check the ET. I am ordering 275-35r18 to go all around, and I am currently attempting to get concrete numbers on the proper backspacing as well.

When I get back I will provide my ET number to allow you to mirror the acceptable and fender clearing setup I have if you like. I can provide some pics as well. dunnman99@yahoo.com

I am not particularly happy with the "drifter" setup from the previous owner so so I am working on getting CIEN suspension with the the NISMO S-tune rates and -20/-25mm ride height.

Ping me back and hopefully I can help you a bit. I also would love to hear other's ideas. I am preparing to roll my rear fender lip when I return after the new year. I have the professional tool and fender rolling equipment now.

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