What are the widest tires you can fit on the new GTO?
245s seem a little small...

245 in the front. 275 in the rear however not all brands will fit without some fender rolling.
:ph34r: :ph34r:

any idea of what the offset of the rear wheels are and their width?
It might be possible to play the widths and offsets to fit some 295s without rubbing. I'll have to take some measurements on the inner fenders, suspension and brakes to see what the max offset I can use without rubbing the suspension

Originally posted by Tails@Jul 9 2004, 01:56 PM
245 in the front. 275 in the rear however not all brands will fit without some fender rolling.
:ph34r: :ph34r:
What is the widest you can put on the stock wheels. Would 255's work?

Getting ready to order tires from tirerack.com in the next few days and if i can go with 255's that would be bitch'n!

Ya think? I'm not sure. Everyone who has looked into it says no more than 245s up front. Some have even had 245s rub on a strut. Taking that as a given, going to 255s out back gains you less than half and inch of width, introduces a speedo error and prevents you from doing normal rotations. Is it worth it???

Originally posted by gto_in_nc@Jul 12 2004, 03:30 PM
Ya think? I'm not sure. Everyone who has looked into it says no more than 245s up front. Some have even had 245s rub on a strut. Taking that as a given, going to 255s out back gains you less than half and inch of width, introduces a speedo error and prevents you from doing normal rotations. Is it worth it???
I hear ya! 245's it is. I'll wait until the next tire change for 18" wheels and then i'll go 275's in the rear.

How does going with a wider tire introduce speedo error? Are there standard width/sidewall ratios for these tires?

There are standard width to sidewall ratios - the problem is that these ratios are not intended to maintain constant tire heights. We're generally only talking a percent or two but it is a factor that needs to be considered. If, for instance, you go from the standard 245/45-17 to a 255/50-17, you introduce a 5.3% error. Going to a 255/40-17 is a 2.5% error in the other direction. A 255/45-17 is off by 1.4%...

Well, you'd NEVER want to increase width and aspect ratio if you care about your speedo and gearing.

Start at 245/45-17, and you'd either want to go to 255/45-17 and be 1.4% off on the speedo (showing slower than you're really going) or go 255/40-17 and be 2.5% off show faster than you're going.

The slightly shorter tire (255/40) MAY also be less likely to rub, depends on whether the tire is rubbing everywhere along the suspensions travel path or only when compressed.

The 40 series would stiffen the ride and tighten up handling, the 50 would soften things a smidge.

http://www.miata.net/garage/tirecalc.html

Brian

Anyone know how much percent you can be off on tire diameter and have problems with ABS and speed control?

WIDTH..........OFFSET............WIDTH OF TIRE
7.0...............+26/+65.............215/225/235
7.5...............+33/+61.............215/225/235/245
8.0...............+39/+55..............225/235/245
8.5..............+45/+48..............235/245/255
9.0.(MAX).........+48................245/255
REAR ONLY
8.0................+36/+65.............245/255
8.5................+42/+65...............245/255
9.0.................+48/+65...............255/265/275
9.5................+55/+64...............265/275/285

OFFSETS GREATER THAN SHOWN ABOVE WILL RUB ON REAR
FENDER LIP. (25MM FENDER LIP)

It doesn't even seem like they built this car to be fast. Wide tires won't fit and it's a coupe that weighs over 3700 pounds dry.

I think you need to get out of the F-body mentality here for just a minute to see the big picture. There is more to a car than straight line acceleration. The GTO is hardly a slouch here either.

Remember where the GTO came from. The Holden Monaro, basically a coupe version of their Holden Sedan based on the Opel chassis. It WASN'T designed to be a straight line rocket. More of a "European" sports cruiser. Handling with some performance to back it up.

Now it becomes the GTO, get the most powerful engines the chassis have ever seen and YES the size of tire is lacking. A 225 series is just fine with a sedate V6 like you could get with the Commodores or Catera or the like which the GTO is based on. 245's are adequate. But with an independent rear suspension setup it's a little bit harder to get the wide rubber underneath there unlike the "live" solid rear axle of an F-body.

So in a way, you are correct, it wasn't designed to be a street terror in a straight line. But I'll tell you this. It handles like a dream and I don't lack for power with just my 350 HP from the LS1.

As for the weight, once again, it was designed for the brutal Aussie roads and has a lot of "beef" to it. It doesn't bother me at all as I don't think we will be hearing issues about body stiffness and squeaks and rattles like you hear from EVERY F-body owner. The GTO is a Grand Tourer in the truest sense of the word and NOT a bare bones straight line warrior. But hey that's what the aftermarket is for. ;)

Ask Howie if his Orange 455 2004 GTO is fast. :o

With all that said look for some of these issues to be addressed in the next gen GTO due out in 2007 model year. :D

EVERY f-body owner?? My 2002 Camaro has no squeaking. Also, you say that your LS1 in your GTO doesn't lack power, but I guarantee that MY LS1 equipped Camaro would be faster in a straight line and on a road course. It's faster than the Mustang. That's more than what can be said for your GTO.

Yes, I hope they clean up the GTO for 2007. It is a sports car, right??? Even though it can't keep up with some stock sedans from Cadillac and Chrysler.

Originally posted by jak112460@Jan 4 2005, 05:24 AM
Anyone know how much percent you can be off on tire diameter and have problems with ABS and speed control?
As I understand it, both ABS and TC look at variations of wheel speeds between the four wheels (in other words relative comparison of how fast the wheels are spinning). Therefore changing sizes wouldn't affect them because all tires would be spinning faster or slower.

For tire size to affect these systems, I think the ABS/TC system would have to be comparing gear selection+RPM to obtain a "correct" drive ratio at a given speed and then see if that matches wheel speed.

Also, you say that your LS1 in your GTO doesn't lack power, but I guarantee that MY LS1 equipped Camaro would be faster in a straight line and on a road course. It's faster than the Mustang. That's more than what can be said for your GTO.

Good for you. :rolleyes:

What are you 12? Whatever the case drop it and back to topic of the thread. Continue and there will be consequences.

To clarrify some things, the 300C is slower than the GTO, look at the numbers, equal power and the 300C weighs 4000 LBS.

The Cadillac cars that can beat a GTO are the CTSV, a LS6 powered CTS costing 50 Grand. Why would an 04 GTO not loose to that, no Fbody would win either.

The GTO has beaten every mustang its been compared with in performance test, Lets not start an argument saying the obvious but an IRS suspension is going to handle a road coarse better than a live axle setup.

Originally posted by 35thSS_5_flat@Feb 10 2005, 04:16 PM
EVERY f-body owner?? My 2002 Camaro has no squeaking. Also, you say that your LS1 in your GTO doesn't lack power, but I guarantee that MY LS1 equipped Camaro would be faster in a straight line and on a road course. It's faster than the Mustang. That's more than what can be said for your GTO.
And my '01 C5 would have ate your f-body alive, what's your point? There's always going to be someone faster, no matter how fast your car is. My A4 '04 GTO clicked off a 13.5 bone stock on stock tires, pretty much on par with many stock A4 f-bodies. I've built C4s, C5s, f-bodies and had my hands in a couple C6s already so I'm not some ignoramus talking out of my rectal cavity here. Do a search online about my friends' shop, Cartek, and you'll see what kind of performance I'm used to dealing with. I won't post a link so as not to violate board rules regarding non-sponsor advertising, but google should get you there. If you'd like to continue the f-body vs. GTO discussions, please start a new thread in the appropriate section so this thread doesn't go more off-topic.

check out BMR Fab. they did some adjustments on i believe,the inner well on the rear and got something like another,inch for width... just my 2 cents...

Originally posted by 35thSS_5_flat@Feb 10 2005, 04:19 PM
Yes, I hope they clean up the GTO for 2007. It is a sports car, right??? Even though it can't keep up with some stock sedans from Cadillac and Chrysler.
You shouldn't believe everything that's written in a magazine....

Originally posted by Orbit Orange@Feb 9 2005, 08:54 PM
...* Now it becomes the GTO, get the most powerful engines the chassis have ever seen and YES the size of tire is lacking.* A 225 series is just fine with a sedate V6 like you could get with the Commodores or Catera or the like which the GTO is based on.* 245's are adequate.* But with an independent rear suspension setup it's a little bit harder to get the wide rubber underneath there unlike the "live" solid rear axle of an F-body.*

... As for the weight, once again, it was designed for the brutal Aussie roads and has a lot of "beef" to it.* It doesn't bother me at all as I don't think we will be hearing issues about body stiffness and squeaks and rattles like you hear from EVERY F-body owner.* The GTO is a Grand Tourer in the truest sense of the word and NOT a bare bones straight line warrior.* But hey that's what the aftermarket is for.* ;)
In fact Holden/HSV began selling the 300kW (402 DIN hp?) GTS in the current chassis way back in 1999, that is before Corvette offered 400hp. See LINK (http://f2.autospeed.com/cms/A_1553/article.html). Despite being shod with 235mm tyres, contemporary road tests claimed GTS outhandled similar era/similar power BMW M5 V8 & was clearly quicker around Nurburgring's Nordshlieffe

As to the 'beef' of Mustang & F-body as compared to Holden, I doubt anybody will get rich trying to sell subframe connectors etc for new GTOs :lol: