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My experiences with bigger wheels
#1
Ok, as the subject has shown up on several threads and somebody asked me if I’d had any issues running bigger wheels on the Mustang, I decided I would post some of my experiences.

I converted all the measures I took from metric to inches using an online converter. So, while I hope the numbers are accurate, there is no guaranty. (Remember: We Europeans use the metric system, which is why a Quarterpounder is called a “Royal with Cheese“!)Cool

As for my car, it has been lowered about an inch using the shorter Mustangs Unlimited front springs (the blue ones) and rear leaf springs with a shallower arc.
The fenders are stock, no rolling or other alterations.

My Mustang originally came equipped with Mag 500 rims and F60x15 tires.
Now, I’d be glad if somebody could provide me with more input on this one, but I’ve been told that, converted to the new metric sizes, this is somewhere in between 225/60/15 and 235/60/15.

I used to have 255/60/15 on American Racing Torq Thrust rims with the standard -6 offset.
Suppose the above info is correct, then these tires were about 3,6 cm (1,3 inches) larger in diameter than the stock tires.
There were no problems with running those on all 4 wheels.

A while ago, I switched to 18 Inch OE Bullet wheels intended for late model Mustangs. 9x18 for the front wheels with a 255/45/18 tire and 10x18 rims on the rear axle with 285/40/18 tires.
These two sizes provide the same overall wheel diameter which is by the way the same as the one for the 255/60/15. (Again about 3,6 cm/1,3inches bigger than stock)
This is what it looks like on the car: EDIT: this particular picture was taken before the car was lowered, still with the bigger tires up front. Check further down for the update.!
   

The rear 10x18 rims feature a 45mm offset and a 19cm (7,48 inch) backspacing. I use 45mm spacers on these rims, so I basically eliminated the offset.
   

So we can say we got a 0 offset wheel with a 13, 5cm (5,32inch) backspace. (19cm-45mm=13,5cm).
With this setup, the distance between the rear lip of the wheel and the leaf spring is 6cm (2,36 inch). The clearance to the steel mounting for the axle rebound bumper is a little smaller. Unfortunately I was not able to measure it exactly, but it was at least 1,6 inches from the wheel. Then there is always the possibility of trimming the outboard edge of it.
   

Based on this info, it is pretty safe to assume that even a rim with a 7 inch backspace could be used (Trimming of the edge of the rebound bumper mounting may be necessary).
Remember the fenders on my car have not been rolled. With rolled fenders, I guess that it should be possible to get a 12 inch rim in there. (That’s an estimate! Don’t nail me on that one!)

So much for the rear wheels.

Now, up front things look a little less optimistic.

Here I have a 9x18 wheel with a 35mm offset and a 16cm (6,3inch) backspace. The spacers are 40mm, giving us a -5 offset. So in theory we have -5 offset rim with 4,72 Inches of backspacing. (Again backspace of the rim minus spacer) .
With this setup, the wheel just barely clears the upper control arm. I could not measure it, but I could barely squeeze my little finger diagonally in between the wheel and the upper control arm.
It's a little hard to see on the pic, but you can see that the upper control arm protrudes into the space inside of the rim.
   

A 17 inch wheel with the same offset and backspacing would not fit!!!! It would rub against the upper control arm, whereas the 18 inch rim clears it by fractions of an inch because of it’s greater diameter.

Even on the 18 Inch rim, the 4,72inch backspacing (with offset-5) is the max you can go, because again it would hit the upper part of the upper control arm.
If you use a wheel with no offset whatsoever, don’t go larger than 4,5 backspacing or make sure you got enough fender clearance on the outside, so you can put a spacer between the car and the wheel!


With this setup fender clearance is no problem. Remember the car is about 1 inch lower than stock and the fenders have not been rolled.
In order to lower the car further you'd have to roll the fenders or reduce the diameter of the front wheels by using a lower aspect ratio on the tires so they match the original size.
To me that was not an option, as I do not like the modern "low profile" look on vintage cars. I think this setup has enough rubber showing so it doesn't look like "Pimp My Ride".
On the rear axle there is no problem lowering the car, as there is enough room for it.

I hope this helps when you plan on going for bigger wheels.

Important: This is, what I measured on MY car with MY wheels. This information is only meant as a guide line and I will not guarantee that it is the same on all cars.
Same goes for the metric to inch conversion. As I said, I used an online converter and while I hope it converted correctly, please don't take it for granted! I posted the metric measurements, so, when in doubt, make your own conversions!
[Image: 1z21rv4.png]

Mike

"If I were you...... I´d rather be me." Tongue

Check out my video:
http://www.7173mustangs.com/thread-my-mustang-in-action

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#2
Thanks for the info
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#3
Good Info.How does the car ride and handle?
[Image: 20r9ylt.jpg]
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#4
can you post up a side view of your car ???

73 ragtop; 302, 335HP, edelbrock carb & preformer; c4 with 2000 stall and shiftkit; 3:55 auburn limited slip; hedman shorties; quiet mufflers

factory air; tilt wheel; 99 sebring buckets; power windows; sound system in progress
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#5
It is a real improvement!
The car feels and handles almost like a new car.
The steering is tight and on the spot, the ride's really smooth and it corners like it's on rails. Ground adherence is superior.
And as I often travel on German Autobahns, I often push her up to about 110-120mph and she still rides smoothly and feels safe.

I always had issues driving in the rain, because I wanted to have those almost period correct RWL tires.
With the Coopers driving in the rain was almost like driving on ice.
With the modern Toyo Proxes tires there is no difference between dry or wet roads. That is the most important thing for me.
(01-06-2011, 01:03 PM)mudbilly Wrote: can you post up a side view of your car ???


Yup, here it is:
This is lowered with the 620 lbs, one inch lower coils. It still sits too high to look good!


Attached Files Thumbnail(s)
   
[Image: 1z21rv4.png]

Mike

"If I were you...... I´d rather be me." Tongue

Check out my video:
http://www.7173mustangs.com/thread-my-mustang-in-action

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#6
The car looks awesome with those wheels. I will be replacing my wheels soon.
I was wondering if you can you check the inside front part of the rear wheel, I think that is the smallest clearance area and give an approximate measurment?
[Image: mustangnight010.jpg]
1972 Mustang Convertible 351C 4V
1966 Ford Galaxie 7 litre-4speed

Jorge
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#7
Mike, I really like the look you've achieved. Nice combination of traditional and modern.
Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

[Image: 1_12_09_14_10_15_11.png]
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#8
as soon i get my mach 1 back from the body shop i will have the 2004 cobra brake system waiting for it. therefore, 17 inch minimum rims wheels be required. with the kit, the 94-2004 mustang wheels are required. i just bought a set of magnum 500's for my wife's 07 gt which look awesome. i was thinking of doing an 18x9 in the front with is for a 94-04 mustang and doing a 20x10 in the rear but its for a 05-11 mustang. might have to use another spacer in there for the 7.2 backspacing.

i have figured out by most people that our car's can easily swallow up a 11-12 inch wide wheel. i had my rear fender rolled so it shouldn't be too much of an issue.

even if i don't want to go with the 05-11 mustang magnum 500 in the rear i'd have to go with the 18x10 in the rear and maybe just send the wheel to a wheel company that widen wheels out. and maybe stretch the offset out to a 11-12 to push the wheel closer to the fender lip.
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#9
Guys, Here's an awsome tool for sizing & comparing wheel tire combo's
I used this when setting up my 71 Camaro (I know Chevy Dodgy) & when I did 20's on my 04 350z Works really well & the combos it gave me on both cars fit perfect...

http://www.rimsntires.com/rt_specs.jsp




   
LOVE OF BEAUTY IS TASTE..THE CREATION OF BEAUTY IS ART
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#10
(01-06-2011, 06:09 PM)jorgem2 Wrote: The car looks awesome with those wheels. I will be replacing my wheels soon.
I was wondering if you can you check the inside front part of the rear wheel, I think that is the smallest clearance area and give an approximate measurment?

Will do, but it may take a few days. Probably the beginning of next week.
Do you mean the distance from the tire's tread to the rocker panel area or from the back of the tire to the wheel well?
Yours looks cool by the way! Is that a 10x15 Mag on the rear axle?


(01-06-2011, 10:22 PM)xoliex Wrote: as soon i get my mach 1 back from the body shop i will have the 2004 cobra brake system waiting for it. therefore, 17 inch minimum rims wheels be required. with the kit, the 94-2004 mustang wheels are required. i just bought a set of magnum 500's for my wife's 07 gt which look awesome. i was thinking of doing an 18x9 in the front with is for a 94-04 mustang and doing a 20x10 in the rear but its for a 05-11 mustang. might have to use another spacer in there for the 7.2 backspacing.

i have figured out by most people that our car's can easily swallow up a 11-12 inch wide wheel. i had my rear fender rolled so it shouldn't be too much of an issue.

even if i don't want to go with the 05-11 mustang magnum 500 in the rear i'd have to go with the 18x10 in the rear and maybe just send the wheel to a wheel company that widen wheels out. and maybe stretch the offset out to a 11-12 to push the wheel closer to the fender lip.

I wouldn't know about having the wheels widened or modified, as I haven't heard of a firm here in Europe that offers such services. If there is one, the whole process would most certainly be more expensive than a new set of wheels.
The good thing about spacers is that by carefully choosing their size you can position the wheel right where you want it in the wheel houses.

[Image: 1z21rv4.png]

Mike

"If I were you...... I´d rather be me." Tongue

Check out my video:
http://www.7173mustangs.com/thread-my-mustang-in-action

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