245/45R17's are pretty common place tires, 235/50R17's will be more expensive to replace (until more cars use them). However I thought something was mentioned about regs in place for snow chains??

Could be wrong but I thought I heard a squeak about that.

 

Me too, I'd prefer a 9" rim. 255's can definately fit on an 8" rim as you said.

For me it'll be 18x9 for sure. Question is: 255's or wider? It will depend on cost and whether I buy the tire/rim upgrade from ford.

The above pics I posted really show the difference from the quarter rear view.

The improvement is very noticable from the rear as well.

 

Yes, I believe you are right. Thai-Tang did say something to steve (galaxie) and I about being able to put snow chains on it. Not sure if that's part of what restricted the width. I think the width was just chosen to be the best for engineering reasons to go with 17's.

 

if I was to get a 9 ince rim. I would go larger. 275's on the front and 315's on the back. now thats fatty!!!!!

 

if I was to get a 9 ince rim. I would go larger. 275's on the front and 315's on the back. now thats fatty!!!!! [/b][/quote]
That would look sweet

Reasons why I wont' do that as much as I would like to:

- can't rotate the tires
- cost

To keep the same tire size all the way around, I think the upper limit is 275's. This is why all four of my tires will be 255, 265 or 275's.

Problem is, the 45R18 tire size is pretty rare and expensive. I'm hoping that because Ford is going to use them in 06, supply will increase and prices will drop. However, Ford will be ordering 255's so I'd expect those to be the cheapest.

I'm willing to spend a decent amount on rims and tires, but I don't want to go poor each time my tires need replacing either.

 

Dan/Boomer,

You have a good list going. You may want to add the following:

- Weight
- Unsprung mass
- Rolling Resistance

The 05 Mustang handles well because of new suspension kinematics and improved weight distribution. This allowed Ford to go with narrower tires to realize the benefits above.

The good news is the wheel and tire package is very tall so you can easily package larger wheels and shorter sidewall tires without running into load carrying capacity issues or rim strike through. B)

 

The gist of what Hau Thai-Tang told me was (I am paraphrashing, and going off of memory)

There are government standards (or SAE??) which basically state that you have to have "X" amount of clearance in each wheelwell for snowchains.

This clearance issue was for the larger and wider 18" wheel and tire package, and that was one of the challenges of the '05 in Hau's words. Because they went to a wider tire and overall diameter, the dimensional size of the wheel wells had to grow.

With the 17's the width is not resitricted at all, because the largest (soon to be available) size is the 18" wheel.

Pony_chief, I think you are totally right about the drastic suspension improvements resulting in not needing wider factory tires. You sound like you read some vehicle dynamics books in your time.

 

Bf goodrich 275 40 R18

 

No offence but I don't see the logic on spending 25K+$$ on a car, even more on upgrading the rims and then trying to save a few bucks by not getting a better looking and handling tire combo

You only live once, so might as well get big wheels

 

That's saying that it is worth it to you to spend twice as much on tires per year just for the uneven wear. If that's cool by you, good, but it doesn't make sense to a lot of people.

I ran different sized front/rears on my '88 GT. If I recall correctly, I ran 225/50-16's on the front, and 245/45-16's on the rear.

In dry weather, the combination was great. As long as the road was clean (not dusty).

If the road was dirty, or it was wet, the roadholding was worse than stock. The car hydroplaned pretty badly.

That's running the German made version of the Goodyear Eagle (same tread design as the stock tire, but with stickier tread compound and lower life).

 

That's saying that it is worth it to you to spend twice as much on tires per year just for the uneven wear. If that's cool by you, good, but it doesn't make sense to a lot of people.

I ran different sized front/rears on my '88 GT. If I recall correctly, I ran 225/50-16's on the front, and 245/45-16's on the rear.

In dry weather, the combination was great. As long as the road was clean (not dusty).

If the road was dirty, or it was wet, the roadholding was worse than stock. The car hydroplaned pretty badly.

That's running the German made version of the Goodyear Eagle (same tread design as the stock tire, but with stickier tread compound and lower life). [/b][/quote]
Exactly M1.

There's spending money on a nice wheel/tire combo (which I'm willing to do BTW), and then there's spending twice as much money on it. On tires that wide and large, you're talking a lot of money.

And, if you want to get technical about it.....Thai-Tang said the weight distribution (52/48) is optimized for a car with the same size tires all around. A 50/50 weight distribution is used for cars which have larger rims/wider tires in the rear.

I'm not saying it doesn't look good, because it really does. But it costs a lot and the uneven wear can hinder performance. As a result, it isn't worth it IMO.

 

Will performance be hindered by really wide tires? more rubber on the road = more friction = loss of performance and economy. That was my recollection of it.

 

Well, you get more traction so acceleration should be quicker at the start. However, larger wheel/tire combo's are heavier and there is more rolling resistance. Not sure if you come out positive or negative as far as 1/4 mile times. My guess would be slightly negative but someone correct me if I'm wrong.

 

You are right on that fact, larger and/or wider tires reduce efficiency by increasing friction and increasing rolling weight.

Tests have been done on models with factory wheels and tires, then +1 and +2 wheel and tire fitments. The outcome will almost always be the same, the larger the wheel and tire, the slower the car will run the 1/4 mile, 0-60mph, while reducing fuel mileage.

Where the above does not logically apply is if the power being put to the wheels is easily overcome, thereby decreasing traction enough to pose a safety risk. I think Ford's thinking in the matter is "TRACTION CONTROL" thereby allowing them to place a narrower tire on the car.

What we need to remember it the extra height increases rolling diameter, which allows a larger tire footprint, thereby increasing traction.

 

Wider tire.... more grip, but lost speed/gas mileage
Takes more energy to rotate that mass.

Its a give/take situation....plus at what point is a tire too small for that specific application to transfer that power.

I think the 235-255 will be nice

 

Hence, the old school drag car look with fat tires in the rear, skinny little tires in the front.

 

Well I am mostly talking from the looks point of view. Actually from what I have seen in the pictures so far the 05 model doesn't really need different tires front and rear, because the stance in the rear has improved a lot over the SN95. That was actually the car I was thinking about. If you put same size tires on that car it just doesn't look right. 275 in the rear starts to do it (though not perfect) but 275 up front sticks out too much and sure doesn't improve steering. 245/45/17 front and 275/40/17 rear have the exact same height and improves the looks noticably. And let's be honest, driving characteristics in the wet are crap no matter what tires you put on it. Hopefully the new 05 has improved a lot in that field, which shouldn't be too hard.

 

With the increased track (pushing the wheels farther out) and the lower stance, the car looks like it has fatties even with 255's IMO. I'll see if I can find a pic.

275's may stick out at the front a bit. I'm worried about that. As a result, I may go 255's all around.

Basically, if you can afford it, go with different sizes for sure.

This looks good IMO.

 

I think the 255s on the 18s look almost perfect.

 

The price for the OEM 17" tires on the Tire Rack is $140.00. That seems to be a reasonable price, very similar to the stock Goodyear Gatorbacks.