How Wide Is Too Wide?

[iplen]

I know people love the idea of wider is better, but there is a point on a track where the tyre simply gets too wide to work properly. So with an an R32, in a very moderate state of tune (300awkw will be all I chase) and not a track weapon, Just a weekend warrior here and there, would 9.5 inch be getting too wide? Then what size tyre (17" wheels)

[ARTZ]

POST EDITED..

sorry iplen I didnt see the bit that said GTR

[The Bogan]

AS BIG AS YOU CAN FIT UNDER THE GUARDS WITHOUT RUBBING OR HITTING ANYTHING.

Rubber = grip so the more rubber you got the less understeer, more traction you have, My RWD boat runs on 265/40 17 all round on a 10" rim on track days, it has helped dial out some understeer and helps with traction, you can do this by playing with you suspension but for a street car that sees the track now and then you cannot beat size for a quick fix.

My street tyres are 245/45 17 on the stock R34 rim (17 x 7.5)

Also only use good quality HiPo tyres (Semis Formula R), cheaper tyres will go of really quick and youll just slide around destroying them.

[iplen]

Not 100% true, there is a certain point where the force down is not enough to generate traction across a wide tyre, this was what a mate who runs an open wheeler was explaining to me. His open wheeler for example with no downforce would be better on narrower tyres.. Happy to be told otherwise, but this bloke is pretty cluey

[ARTZ]

My RWD boat runs on 265/40 17 all round on a 10" rim on track days,

wow they fit without scrubbing..?

i would think thats a good size for a 300kw gtr as well.

[T04GTR]

AS BIG AS YOU CAN FIT UNDER THE GUARDS WITHOUT RUBBING OR HITTING ANYTHING.

Rubber = grip so the more rubber you got the less understeer, more traction you have, My RWD boat runs on 265/40 17 all round on a 10" rim on track days, it has helped dial out some understeer and helps with traction, you can do this by playing with you suspension but for a street car that sees the track now and then you cannot beat size for a quick fix.

My street tyres are 245/45 17 on the stock R34 rim (17 x 7.5)

Also only use good quality HiPo tyres (Semis Formula R), cheaper tyres will go of really quick and youll just slide around destroying them.

i agree. ps, where did you find 17x10 rims?

[simpletool]

im not a big fan of huge wheels either man, prefer function over form.. ;)I think 17x9.5 on the rear with 8.5 on the front would be near on perfect i think..235/45s on the font and 255/40s on the rear..Thats what I have anyway

Just to clear up the above. Since you have a GTR then you need to run equal size tyres front to rear - best to run the exact same rim and tyre size so that rotational speed is identical. You probably already know that.

Then run the width as suitable for the maximum tyre that will fit under the guards without rubbing on full lock and usable suspension travel. I have no idea what this is.

If you are running semi or slicks then 17's are fine and just as good as 18s as long as they fit over the brake package. If you are running road tyres then 18s are better than 17s for a given tyre. Obviously bigger wheels allow a bigger brake package which can be handy.

[ARTZ]

yeah I edited that post^^

[simpletool]

Not 100% true, there is a certain point where the force down is not enough to generate traction across a wide tyre, this was what a mate who runs an open wheeler was explaining to me. His open wheeler for example with no downforce would be better on narrower tyres.. Happy to be told otherwise, but this bloke is pretty cluey

Not entirely sure what he is referring to but he can just run a softer compound or flatten out the camber (depending on what the problem is) if he feels the tyre is too wide. Most serious racing classes have tyre width limits for a VERY good reason.

The GTR is a heavy car and loves FAT tyres.

[The Bogan]

edit: Sorry, I just put the tape on the rims and they come to 9.5

The front just touch the sway bar on full lock but are OK with a 5 mm spacer and the inner guards need to be removed, the rear just fit but do scrub a bit on big bumps on the rolled and slightly pumped guards.

Ride height is 350 front 340 rear.

Got the rims from Pete from ADVAN Performance a couple of years ago, they were the rims from his shop car Gracer, old VOLKS.

I like them alot, they do need a reco though.

[-Jimmy-]

A common width/offset for a lot of japanese rim makes for the GT-R is around 17x9.5J +12 (TE37, CE28N, Nismo LMGT4, Enkei RPF01, etc etc). You could run a 265/40R17 on that and I think it would fit nicely.

Edited July 13, 2011 by -Jimmy-

[KiwiRS4T]

Tyres will ideally be the same width as the rims so that the sidewalls are perpendicular. This is how they work best. People use "stretched" tyres (tyres that are too small) for cosmetic or fashion reasons or perhaps so that they can spin their wheels with less power but if you use the charts put out by the tyre manufacturers you will be fine.

[funkymonkey]

after running 2 widebody skylines I can tell you for a fact that having a strong engine, and 355 rubbers on the rears means something else HAS to give. In our case it was usually clutch, driveshafts or axles

[ARTZ]

after running 2 widebody skylines I can tell you for a fact that having a strong engine, and 355 rubbers on the rears means something else HAS to give. In our case it was usually clutch, driveshafts or axles

I havent had any widebody skylines but I have read enough books to know this is true..

also can play havoc on steering joints wheel bearings bushes etc..

Like most things you modify on a car everything has a chain reactiom unless its done as part of a complete package you quickly reach the point of diminishing returns and quite often less is more..Balance is key

the people that are fast know this but their cars often dont look as fast standing still.. Just like winning a race this week is meaningless if you kill your car in the process and cant make it back to race again next week....

PS..yes i realize i sound like a parrot quoting cliche phrases..

[bigmikespec]

after running 2 widebody skylines I can tell you for a fact that having a strong engine, and 355 rubbers on the rears means something else HAS to give. In our case it was usually clutch, driveshafts or axles

What tyres were you running with the 355's? I have been thinking if a 12" wide rim would be possible to fit underneath a R33 GTR with right offset and guard mods.

[Takahashi GTR]

I run Kumho Ecsta SPT 285/40 all round on my GTR, on an 18 inch wheel, rolled and flared the guards a little and they still stick out past the guards which I like. Only rubs when parking on full lock or with the occasional flick....

Looks mean.

[ARTZ]

my GTR Only rubs when parking on full lock

Looks mean.

hehe yeah my Ferrari only gets wet when I wash it

[funkymonkey]

What tyres were you running with the 355's? I have been thinking if a 12" wide rim would be possible to fit underneath a R33 GTR with right offset and guard mods.

http://www.skylinesaustralia.com/forums/topic/84208-wheel-sizes-offsets-for-skylines/page__view__findpost__p__1881822

It's an original kakimoto widebody (not the skylineimports copy that has the suspension all out of whack).

[luke gtr]

ive got 17x9.5s at the moment and was looking at this last week...

if you run 255/40R17, you have the extra grip of the wider tyres, and are about 4mm different to the original 225/50R16s(im pretty sure) fitted...

shouldnt throw your speedo out.

[Sopuff32]

Ive got 18x9.5+22 wrapped with 255/40R18's on my 32 which makes 400hp and for street use there are no problems (except on full lock when parking), traction and understeer arent a problem for street driving.

Tested the speedo on a dyno and sits almost perfectly in sync with road speed.

In my opinion for street use with your power goal of 300awkw 245's are sufficient.