Who's Running Wider Rear Wheels&tyres On A Gtr?

[Brezza]

Hey people,

just wanted to start a thread to find out whether there are many people out there running split width rims and tyres on their GTR.

i know people have raised issues about the ATESSA, and rolling diameter of the wheels.

but i am currently running a set of 17's and my front rims are 9in wide and the rear are 10in wide.

my car is a R32 GTR

i got 235/45R17 on the front and 255/40R17 on the rear.

using this link i calculated my rolling radius and circumference to be

http://www.club80-90syncro.co.uk/Syncro_we...0calculator.htm

front circumference 1962mm

rear circumference 1939mm

DIFFERENCE of 23mm

front radius 312mm

read radius 309mm

DIFFERENCE 3mm (which is 6mm in diameter)

i know its not equal, but i am hoping to keep the same size for the front and get a 265/40R17 on the rear, which will make the Circumference 1964mm (Difference of 2mm) and Radius 313mm (Difference of 1mm)

does anyone else favour the added traction on the rear of a GTR??

[djr81]

Based on some scientific sampling of the 8327 threads on this subject there are two people who favour running larger rears tyres on the rear of an R32 GT-R. Neither of them should be listened to.

There are many good reasons not to.

There are no good reasons for doing so.

Try a search.

[blind_elk]

Based on some scientific sampling of the 8327 threads on this subject

I would have thought there must be nearly twice as many as that

[Sydneykid]

Put the guy out of his missery, your car has 65% of its weight over the front wheels and you want to put a larger tyre on the rear. Does that sound logical to you?

Cheers

Gary

[Beer Baron]

I say do it. it's an awesome idea. it's just that in the 20 years that GTRs have been around no one else has thought of it or tried it. maybe ring Garage Saurus, Mines, M-speed, HKS, Prime Garage, and all the other GTR racers and workshops you can think of and let them know of this breakthrough in GTR performance. a way to give the car more understeer. it's also great as it means no more pesky wheel rotations to extend your tyres life, so you get to see your mates at tempe tyres more often. you will also have the benefit of eventually triggering your car into RWD and no ABS mode, so it'll become a real mans car, just like a 1983 model holden commodore. get ready for some awesome skids!!!

[funkymonkey]

and here I thought running 10.5"x18 at the back and 9.5"x17 on the front of my GTR was revolutionary shit.

dangnammit.

[NickR33]

Put the guy out of his missery, your car has 65% of its weight over the front wheels and you want to put a larger tyre on the rear. Does that sound logical to you?

Cheers

Gary

even GTSt's handle better with same width wheels front and back... and you can rotate them when you chew through rear tyres

I've got 10" wide fronts on the GTR and it still understeers on a skid pan... can't imagine how much of a pig running a staggered set would make it... eeek

[djr81]

There is a rubber chicken prize for whomever can stop a GT-R from understeering. I have my hopes. The rear anti roll bar I made out of scaffold tube should hoik that inside rear atleast 3 inches off the deck.

Being serious it is no good having traction in a car that won't go around a corner. Traction is easy to get in a GT-R. Finding front end grip is very hard.

But the Baron is right. VH Commodore & R32 GT-R. Same same.

Edited July 24, 2009 by djr81

[NickR33]

ooooh group buy for scaffold tube sway bar?

I've got a heap of neg camber on the front to try and get it turned in... its great on the street, have to have 2 hands on the steering wheel all the time to make sure I don't 'unexpectedly' change lanes

while I'm whoring this thread here's a pic for you djr81... see I still have a few inches to go...

[PM-R33]

Hahaha that's a cool pic.

[funkymonkey]

GTR's come with hyrdo's now?

[Sydneykid]

ooooh group buy for scaffold tube sway bar?

I've got a heap of neg camber on the front to try and get it turned in... its great on the street, have to have 2 hands on the steering wheel all the time to make sure I don't 'unexpectedly' change lanes

while I'm whoring this thread here's a pic for you djr81... see I still have a few inches to go...

Judging by that picture it doesn't have enough caster and/or camber.

And the front spring rate and/or antir roll rate may also be too high.

Cheers

Gary

[bnr#@]

ooooh group buy for scaffold tube sway bar?

I've got a heap of neg camber on the front to try and get it turned in... its great on the street, have to have 2 hands on the steering wheel all the time to make sure I don't 'unexpectedly' change lanes

while I'm whoring this thread here's a pic for you djr81... see I still have a few inches to go...

That pic is most awesome however. I would definitely be getting the full size one of the photographer

[NickR33]

Judging by that picture it doesn't have enough caster and/or camber.

And the front spring rate and/or antir roll rate may also be too high.

Cheers

Gary

the spring rates front and rear are way too high... it has old off the shelf Tein RE's in it which are hard as concrete... something like 12kg/mm... would be more compliant with blocks of wood in there

camber is a trade off for street duties for the moment... not sure how much castor its running but its got Nismo bushes, circuit link set and tension rod set so more than standard

it handles great in wider/faster corners... just has trouble getting around cones on a skid pan... handbrake shoes need upgrading so I can use it more and I need to learn how to drive it better;)

[djr81]

ooooh group buy for scaffold tube sway bar?

I've got a heap of neg camber on the front to try and get it turned in... its great on the street, have to have 2 hands on the steering wheel all the time to make sure I don't 'unexpectedly' change lanes

while I'm whoring this thread here's a pic for you djr81... see I still have a few inches to go...

Soft I tells ya, soft.

Real men run too soft a spring rate & try & make up for dynamic camber changes with too much neg camber. It almost works - until you have to get the car working in slow speed corners.....

[Sydneykid]

Soft I tells ya, soft.

Real men run too soft a spring rate & try & make up for dynamic camber changes with too much neg camber. It almost works - until you have to get the car working in slow speed corners.....

There's bunch of mixed metaphors. I run more caster and less static camber than most but I run more dynamic camber change. For every degree of chassis role I have 0.75 to 1.0 degrees of negative camber built into the front camber curves. I do run soft spring rates with a lot of anti roll but then I can tune the balance quickly on the day with the swaybars. To stop excessive negative camber under brakes I run more than standard anti dive geometry in the front end.

There are lots of "tools" at our disposal but we can only do so much when 60% to 65% of the static weight is on the front wheels. That's where driving technique has to be developed. Slow in fast out has always been the fastest way around a circuit for a 4wd Skyline. If we treat them incorrectly, such as fry the front tyres under brakes, followed by a yank on the steering wheel and then expect no understeer we are truly dreaming. No amount of suspension set up can overcome inappropriate driving technique. Even a perfectly set up F1 car can be made to understeer and a GTR is long way from that..

Cheers

Gary

[Wacky Dee]

someone help me decipher what's being said here ... staggered setups (ie. wider wheels at the back) are BAD for AWDs (GTR) or for any Skyline? Or did I miss the point entirely ?

[djr81]

There's bunch of mixed metaphors. I run more caster and less static camber than most but I run more dynamic camber change. For every degree of chassis role I have 0.75 to 1.0 degrees of negative camber built into the front camber curves. I do run soft spring rates with a lot of anti roll but then I can tune the balance quickly on the day with the swaybars. To stop excessive negative camber under brakes I run more than standard anti dive geometry in the front end.

There are lots of "tools" at our disposal but we can only do so much when 60% to 65% of the static weight is on the front wheels. That's where driving technique has to be developed. Slow in fast out has always been the fastest way around a circuit for a 4wd Skyline. If we treat them incorrectly, such as fry the front tyres under brakes, followed by a yank on the steering wheel and then expect no understeer we are truly dreaming. No amount of suspension set up can overcome inappropriate driving technique. Even a perfectly set up F1 car can be made to understeer and a GTR is long way from that..

Cheers

Gary

Yeah I was just trying to have a laugh based on some of the failings of my set up.

BNR#@ took this of mine. Not sure how close to being right it is, but it appears to work ok. It was only the out lap which explains why I missed the apex by a good metre & a bit.

someone help me decipher what's being said here ... staggered setups (ie. wider wheels at the back) are BAD for AWDs (GTR) or for any Skyline? Or did I miss the point entirely ?

You are correct.

[Wacky Dee]

which ..awd or any skyline ? what's that photo supposed to show ? Sometimes I feel blind n stupid..

[djr81]

which ..awd or any skyline ? what's that photo supposed to show ?

On any R32 Skyline & expecially on a GT-R.

The photo shows just how much neg camber the inside front tyre has compared to the working side & the rear when its cornering.