My experiences with bigger wheels

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luxstang

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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.!

dsc_4306.jpg

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.

013.JPG

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.

014.JPG

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.

016.JPG

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!

 
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luxstang

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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.



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!

dsc_4307.jpg

 
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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?

 
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BigPinoyHunk

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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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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

100_0729.JPG

 

luxstang

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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?



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.

 
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Thanks for the reply, those are 15x 8" magnum 500 all around. I was thinking the clearance on the inner front of the rear wheel, the inside fender is very close there as well as the inner rocker.

 
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BigPinoyHunk

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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?



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.
http://www.weldcraftwheels.com/index-1.html

i also got my wife's 07gt OEM wheels i have being stored in the shed. the mustang is a paid for mustang now and no intent in getting rid of the any time soon. the car has magnum 500's in 20's. i'm thinking about using her original wheels as a plan B. maybe just widen the rear wheels to an 11 wide or even a 12. this way i can get whatever i want.

 

AutoBotMach

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Killer convertible you have :) Great read!

With the 9's how well does it turn lock to lock clearance wise?

I'm currently running torque II's 17x8 with 4.5 bs 0 offset with a 245/45/17 yokohama and global west tubular uppers/lowers and it's a tight fit when turned full lock. Love the fact that you are running nine's i have always wanted to go a bit wider also :cool:

 

luxstang

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Killer convertible you have :) Great read!

With the 9's how well does it turn lock to lock clearance wise?

I'm currently running torque II's 17x8 with 4.5 bs 0 offset with a 245/45/17 yokohama and global west tubular uppers/lowers and it's a tight fit when turned full lock. Love the fact that you are running nine's i have always wanted to go a bit wider also :cool:

Thanks, I'm happy you like it!

Well, now that you ask, I notice that I have forgotten to post this. When you turn to the right, there is no problem at all, but when you turn left, the tire scrapes on the frame rail.

The funny thing is that it did this, even with te 15x7 Torq Thrust rims.

Interesting thing, I know of two other 71s, that do the exact same thing. The one on the right clears, the left one scrapes on the frame.

This never happens under actual driving conditions, not even when you maneuver into a parking space. It only happens when you fully turn the wheel when the car is standing.

Strange....

I don't even think that it is a issue with backspacing. I believe it to be related to the fact that the overall diameter of the wheel is bigger than factory stock.

Your wheel is 1.3inches smaller in diameter, so it should be about the stock size....

I guess that might be my problem.

I will try and go the way of either a smaller aspect ratio (which I will probably not like look wise, because it is too "modern") or maybe get a 17 inch wheel for the front, as I want to lower the car further and there is not enough clearance to the fenders for going any lower.

So my advice, if you wanna be on the safe side: get a 9 if want, but don't let the wheel diameter get too big.

 

madurodave

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I love the look. Wanting to achieve the same.... If I go with your same set-up for my stock 73 but use 9" on all four (18x9 all the way around, with the 255/45/18) what size spacer should I buy? thanks in advance

 

luxstang

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I love the look. Wanting to achieve the same.... If I go with your same set-up for my stock 73 but use 9" on all four (18x9 all the way around, with the 255/45/18) what size spacer should I buy? thanks in advance
That of course depends on the offset of your rims. Mine have 35 and 45 so I went with 40mm on all four wheels. Makes for a -5 up front. For reference: American Racing Torq Thrust D in 7x15 have offset -6, so it´s almost exactly the same. With 18 inch rims you clear the upper control arm, so there should be no problem.

Just one thing though. With those tires (255/45/18) your overall wheel diameter will be larger than the stock wheels. Clearance is not an issue but the car will ride a little high above the ground. That irks me with mine now. If I were you, I´d go with a series 40 sidewall or even with a 245/40/18. That last one is almost exactly stock height and you can lower the car a little up front if you like.

Even without lowering the car, the 245/40/18 will bring your car 1,7 cm closer to the ground than with the 255/45/18.

But that´s only as far as looks and my personal taste are concerned. Running your tire size shouldn´t be an issue.

 
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I love the look. Wanting to achieve the same.... If I go with your same set-up for my stock 73 but use 9" on all four (18x9 all the way around, with the 255/45/18) what size spacer should I buy? thanks in advance
That of course depends on the offset of your rims. Mine have 35 and 45 so I went with 40mm on all four wheels. Makes for a -5 up front. For reference: American Racing Torq Thrust D in 7x15 have offset -6, so it´s almost exactly the same. With 18 inch rims you clear the upper control arm, so there should be no problem.

Just one thing though. With those tires (255/45/18) your overall wheel diameter will be larger than the stock wheels. Clearance is not an issue but the car will ride a little high above the ground. That irks me with mine now. If I were you, I´d go with a series 40 sidewall or even with a 245/40/18. That last one is almost exactly stock height and you can lower the car a little up front if you like.

Even without lowering the car, the 245/40/18 will bring your car 1,7 cm closer to the ground than with the 255/45/18.

But that´s only as far as looks and my personal taste are concerned. Running your tire size shouldn´t be an issue.
Why use spacers? Can't one just buy wheels with the proper backspacing? I've looked into this before with 18 and 17" wheels and took lots of measurements for clearance, but can't find my notes now :( I'm taking a guess here but if memory serves me right, then 17x11's with a 6" backspacing for the rears and 17x8's with 4" backspacing should clear everything without the use of spacers.

 

luxstang

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Why use spacers? Can't one just buy wheels with the proper backspacing? I've looked into this before with 18 and 17" wheels and took lots of measurements for clearance, but can't find my notes now :( I'm taking a guess here but if memory serves me right, then 17x11's with a 6" backspacing for the rears and 17x8's with 4" backspacing should clear everything without the use of spacers.

Yup, you´re right. Your figures should work without problems.

Only trouble is that most wheels in 17-20 inch come with a positive offset to fit modern cars. Like mine that are meant for a 2005 or 2010 Mustang. Same thing if you use wheels like the stock Bullit rims or other modern Mustang rims.

The positive offset causes your wheels to stand too far "inside" of the car. My 10x18 at the rear wouldn´t even turn because they did not clear the wheel well. Same thing up front where the upper control arm did not even allow the lug nuts to touch the threads in the studs. So you gotta use spacers to push the wheels further to the outside so that the wheel sits where it belongs.

Now if you go and buy some Vintage Wheel Works or Boyds or whatever wheels that are made for classic cars, you may find wheels with offset 0. In that case of course you don´t need spacers.

 
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