I don't get it.Increase HP by 40 on GT and go with 235/55's????????Im starting to think I may wait till '06 after all.

 

Why? Because you'll get 18's that are just as skinny?

It's "only" 20mm. It's not like they went to 175s or something like that. (Although, there could be some humor in that...)

Am I being obtuse?

 

Umm, isn't that the beauty of the aftermarket... no one ever said you had to stick with the original stock setup

 

Let's hope the reason why is that with the new suspension and improved grip it provides, the wider tires were no longer necessary to achieve better handling than the previous GT.

 

Must have something to do with gas mileage.

 

true,but why go to 235's when previous GT's and Mach 1's had 245's.I don't understand why ford did that,anybody ask any ford people???

 

Probably a cheaper/better all around tire.

The car had to keep the sportyness but also have a good All season tire for better snow handling. *you may think not, but believe me, lots of people drive their stangs in the winter.

10mm off each tire DOES help traction in the snow (where less is better)
Plus it allows for a bigger sidewall, without wasting a bundle (save money per tire)

It will handle well, 235s aren't BAD....

So lets recap...
Price, Handling in snow, sportiness, overall appeal.

You want a wider tire...buy some 255s+, see how much they cost
I know I'll be getting separated 18s for the summer with 255-275s on them.

 

It the Mustang came with 18" wheels, then it would most likely be a 255/45/18 tire, which is 20mm wider, but it would be on a wider wheel, probably an 8.5" or 9" wheel over the factory 17x8" wheel. This would put slightly more than an inch in the ground for increased traction on acceleration, plus reduce sidewall height a 1/2" reducing sidewall flex.

 

Here are some numbers to chew on:

2004 Mustang GT = 245/45/17. Tire = 25.7" Diameter on 17" wheel.

Now we want to know how tall the sidewall is with the tire mounted on the wheel.

Tire = 25.7" - 17" wheel = 8.7" Total Sidewall height / 2 = 4.35" Tall Sidewall, area between the wheel and the ground.

2005 Mustang GT = 235/55/17. Tire = 27.1" Diameter on 17" wheel.

Tire = 27.1" - 17" wheel = 10.1" Total Sidewall / 2 = 5.05" Tall Sidewall.

This is a .70", or almost 3/4", taller sidewall than a 2004 Mustang with 17's. This will equate to much more sidewall flex when pushing the car into a turn. To make this more counter productive, the new Mustang weighs almost 200lbs more than the 2004 Mustang, now running on a narrower tire. I've said it before, but this would would be like placing 225/55/16" wheels and tires on a Cobra. Imagine trying to put 300hp+ down to the ground on a 16" tire only 225mm wide. The current 2004 Mustang has a full 1" wider tire than a 225/55/16 on a 7.5" wide wheel.

Now imagine a 19" tire, same height as the 17" tire, 27.1" diameter.

Tire = 27.1" - 19" wheel = 8.1" Total Sidewall / 2 = 4.05" Tall Sidewall.

This is only 1/3 inch shorter sidewall than the current 2004 Mustang with 245/45/17 tires. Lastly, lets do an 18" tire.

Tire = 27.1" - 18" wheel = 9.1" Total Sidewall / 2 = 4.55" Tall Sidewall.

This is still 1/5 inch taller sidewall than a 2004 Mustang with 245/45/17 tires and wheels. Again, remember the new Mustang weighs MORE, and more side wall is not necessarily good for handling, but ride quality will improve.

For the 2005 Mustang to be EQUAL to the 1994-2004 Mustang with 17" wheels in terms of sidewall height, you would need a slightly shorter tire, 26.7" diameter on an 18" wheel. This tire would be the 245/45/18. This tall of a tire looks very narrow in 18" spec, so I would prefer a 255/45/18 for the front on an 8" or 8.5" wheel, then a 285/40/18 for the rear on a 9.5" to 10" wheel.

 

That is just shy of one inch! 2.54cm is one inch! That is a pretty big difference in my book!

 

It's the width of my thumb. Big freakin' deal. The patch on the ground is what, 2 inches "long"? I'd think it mattered not. Get loud with me when it's a hand's width.

Oh, and I was mistaken. It's only 10 mm. (245 vs 235) Which is my pinky.

I found the sidewall discussion to be more enlightening, and now it makes sense. 18s it is. Although they'll still be "skinny" (as if)

 

I like the sidewall height on the '05. I would just go a little wider. IMHO sidewalls are starting to get ridiculous....next to nothing if you know what I mean. It's refreshing to see some of it come back again...it's low profile enough. The 05's 18's sidewall is still ok, anything smaller looks to ricey IMHO.

 

Do you think the new '05 Mustang GT will handle better with the 235/55-17's than the 31x10.5-15's Goodyear MT/Rs on my '97 Explorer?

 

Ford has chosen to go with overall bigger wheels on the new Stang. This simply means that the sport/comfy setup now is 17", the sporty is 18" and the tuner 19". Bet Steeda, Saleen and Roush all will sport 19"ers.

Here's a cool site for easily comparison of tire sizes:
http://www.smokemup.com/auto_math/tire_diameter.php

 

I do not think Ford chose to go with bigger wheels and tires, but it was essential for the design to have balance and the correct ride height.

The new design platform will have the floorboard closer to the ground, which means the axle centerline is slightly higher in the body. To accomodate the change, taller tires were "needed" to raise the car to an acceptable ride height. This is also the reason the mufflers are now behind the rear axle under the trunk, not under the rear passenger floor plan like the past 40 years. The positive side effect of that design change was a quiter interior with less restrictive mufflers.

 

The first few years of classic Mustangs had transverse mufflers ~behind~ the rear axle. At least through 70 or so? So make that 25 years of under-the-seat mufflers (grin)

Man, why am I such a bitc_y stickler about old cars?

People replacing the old transverse with aftermarket mufflers shoved them under the rear seats, and luckily they stuck down less than mufflers people hung on their 70's era Trans Ams and Camaros, where they basically ran around with something like 3" of clearance.

 

Yeah you can do that but that would be silly!! If you don't want to spend a lot of money on a pretty good tire try falkens or hankook. I have 255 hankook ventis on my cobra. They handle great,look great and don't cost a lot of $$$. remember not every company makes 255 tire sizes. These are hankook pics!!

 

Yeah you can do that but that would be silly!! If you don't want to spend a lot of money on a pretty good tire try falkens or hankook. I have 255 hankook ventis on my cobra. They handle great,look great and don't cost a lot of $$$. remember not every company makes 255 tire sizes. [/b][/quote]
Pic 2

 

Boomer hit many of the points on the head:

The reason you get 235 55R17 stockers is because:

- cost - its costs more to put on larger tires/rims and that would bump the price up
- winter/all-season traction - Ford wanted a tire that could allow the mustang to travel year-round. That isn't happening on a 255+ or an 18" low profile tire.
- ride quality - many people want the car to ride well. Many buyers not interesting in getting every last 10th of a "g" out of their car will appreciate the improved ride quality that comes with a larger sidewall.

Last, you have to remember that this is the stock tire. Ford intended to offer an 18" option but for whatever reasons (discussed previously) they are not going to in 05. Understand that starting in 06MY, 18" rims will be the upgrade.


As for 255's not looking much different than 235's, I'd like to disagree. The 255's look wider and 10x better IMO. Part of the reason is that they are 20mm wider and part of it is that they are mounted on 9" rims vs. 8" rims. The rim aligns the tire with the inside of the fender filling in the wheelwell better when looking from the side and behind the car.

Example:


vs.

 

I agree with every thing you have said but the 95 mustang cobra came stock with 255/45/17's on 8 inch wheels. . I have even recently put 275's on the rear on my cobra with the same 8 inch wheel. No bulge ,but would prefer the 275 on a 9 inch rim