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Put 18's On And The Torque Gauge Is.....

godzla32

By godzla32,
in General Automotive Discussion

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godzla32 Collaborator

godzla32

Posted
Posted

My Torque Gauge Is Not Working As It Was With The Standard Gtr Wheels Its Constantly On 10?, The Guy I Brought The Wheels Of Said The Same Thing He Reckons Something To Do With Bigger Tres On The Back? Any Truth To This And How To Fix It?

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Guest Variable

Guest Variable

Posted
Posted

I had the same problem on my 32 GTR a while back. Had some 3 month old 255/40 R17 Federals on the back and replaced the fronts with brand new 255/40 R17 Potenza S03's. The difference in rolling diameter was enough to put my torque gauge permantly on about 8. Put the new Potenzas on the back and everything went back to normal.

Laurence Mentor

Laurence

Posted
Posted

There is no law against putting the same size tyres on those rims.

245's will be happy on both those widths. Commodores have 235's on 8" rims

stock BNR34s run 245/40R18 on 9" wide wheels. It is all good dude!

Trivia:... 911 turbos use different diameter front and rear tyres to preload the viscous coupling that transfers torque front to rear.

TurboX Mentor

TurboX

Posted
Posted
all four wheel/tyre combos must be the same on a gtr.

No, you can have different widths front and back but the tyres you use have to have the SAME ROLLING Diameter.

So its just a matter of getting the right aspect ratio of the tyres correct.

Its the same if you get a partly flat tyre, the torque gauge tells you something is not right by running quarter way on constantly.

ferni Grand Master

ferni

Posted
Posted

if you have different size tyres on (that arn't exactly the same rolling diam), the ATTESA picks up that one set of wheels (front or back) is spinning faster than the other set, so it gives you some front torque...

everyone i know with a GTR goes for same size wheels/tyres for this reason, plus we can fit them under our gaurds :D

aybee Experienced

aybee

Posted
Posted

the difference in wheel size may affect it though. cause when you put 245s over 9 inch wheels they will stretch more than on 8 inch. The more stretched, the less upright the sidewalls so the rolling diameter will be less.

or may be less. just a thought. can anyone clarify...

Laurence Mentor

Laurence

Posted
Posted

Yes... that is right. It all depends how smart the computer is

If it is 8.5 vs 9.0 inch and he is using 245/40R18's and lets just assume that 8.5" gives you a perfectly straight sidewall you would have a total diameter of 653.2mm So if we stick them on 9" wheels (6.35mm wide each side) and assume (there is that word again) that the sidewalls are 100% stiff and retain their 98mm length then the according to Mr Pythagoras new effective height would be 97.98mm which is probably something I have stuffed up...

So the difference would be 0.04mm on the total diameter.

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