shelbymustangdan

I am looking to reduce the width of my front tires from 245/45/17 (17x8 rim with 4.5" backspace, 0 offset) to something more narrow. Reason: I can't seem to get the tires to stop hitting the fender on those "wallowing dips in the road" situations, or a "sharp change in pavement height" such as crossing an intersection.

Shocks are relatively new, 1" sway bar added", in the process now of trying to identify the existing coils springs which look like they aren't too old. I do have a 351W (408W) with aluminum intake and heads to take into account as well regarding weight. No AC no power steering.

I cannot roll the fenders due to some body work behind the fender lips. My assumption is that there was rust up there at some point, and someone made a repair.

I do have fender well trim. Even if I took it off, which I do not want to do, it would most likely still hit the fender on occasion.

I am going to buy new rims and tires up front. A 17x7 rim with 4" backspacing and 0 offset. My calculations indicate that moving to this new rim, a 215 tire will move the outer edge of the tire towards the inside by 1.10", and a 225 tire will move the outer edge of the tire towards the inside by 0.935". The fend well lip is about 1".

My questions to those who have non-rolled fenders with fender well trim:
1. Is a 225 tire going to create ANY fender rub?
2. For those who have 215 tires, do you have any regrets of not going to 225s? (i.e. "too skinny")
3. If anyone has found a different solution to my problem, that has not been mentioned, please share.

I have read everything I could find, including the "dodgestang" chart which does not capture what engines (weights) are in involved. I may be dealing with less than adequate coil springs, but hopefully I will sort that out soon.

Thanks in advance!
Dan

67mustang302

No one can say for certain, because there's too many variables. Rims used, brakes used, suspension components used etc. You can probably answer your own question better than anyone, beyond generalizations at least.

That said, it's probably more of an issue with suspension than anything. Most spring and shock setups out there for vintage Mustangs are garbage for performance and suspension control. Bad springs and shocks won't control the suspension well enough to prevent fender rub in a lot of cases.

Ideally, you want 0 rub; realistically you can settle for a tiny bit of rub under extreme circumstances, such as hitting a crazy pothole while cornering etc. But you need suspension that controls the car in the first place.

You can go to narrower tires, but older Mustangs have some understeer problems to begin with; so reducing front traction is one of the least ideal routes.

barnett468

hello;

you must pick a size that does not hit if you do not want them to hit. if you like really wide tires and do not want to butcher your fenders, this size will be less than you want.

get rid if the stupid 8" rims. they do not belong on the front of that car. just curious, where did you hear that you could run 8" rims and those tires on that car?

if someone wants tires that are wider than those that came on the 69 and 70 boss 302 and 429 cars that had their fenders rolled at the factory so they would not hit, buy a new mustang.

put 7" rims on the front with 4.5 - 4.75 b/s and skinnier tires

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67mustang302

You can fit 8" in the front of 67+, but it's pretty intolerant of incorrect backspacing and requires some tweaking to the fenders in most cases. It also requires really good suspension, but you'll rub the fender before you hit the bump stop (if you ever could).

I have 17x8 on the front of my 67, and my backspace is actually not quite deep enough because of the brakes I have...and it doesn't rub up front unless I hit an absolutely crazy bump while turning. I haven't cut the coils though, so it is sitting almost 1/2" higher than it should be ideally and may rub a bit once I do.

Of course, I had to roll the fender lip and loosen the fender mounting bolts and push the fender out as far as it would go. I also have a lot more suspension control on the front of my car, so it doesn't travel nearly as far as most other Mustangs.

barnett468

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Hello shelbymustangdan;


The suspension has nothing to do with whether the tires will hit or not.

Here's one way to definitevely determine if they will ever hit.

remove a front spring

install front wheel

jack it up around 2" at a time.

turn wheel full left and full right every time you jack it up.

it will hit or It will not hit, very simple.

if it hits, using stiffer springs and shocks or travel limiters etc., is a band aid to attempt to compensate for tires that will hit otherwise.

some people fix it right and others mickey mouse it. i've even seen some people do the following:


Hi folks...my name is Mickey and I'm here to fix your oversized tire prob.

. . . . . . . . . . . .


The first thing ya'll should do is simply jamb some of these in yer springs. They're only around five bucks.

. . . . . . . . . . . .


. . . . . . . . . Then yer springs can look like this.

. . . . .

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67mustang302

It's not Micky Mouse suspension on my car. Unless you think Maier coils and custom valved Bilsteins are Mickey Mouse.

Good suspension will limit travel in conditions where it would otherwise move a lot (needlessly). It can prevent the tires from rubbing if the suspension doesn't travel far enough to let the tires contact the fender. It doesn't resolve a mechanical interference through the whole arc of travel, just prevent it from reaching that interference point.

Most Classics are running mediocre springs with terrible shocks, so the suspension moves all over the place when it doesn't need to. If you're setting a Classic up to corner well, then you're typically going to end up with reduced suspension travel as a result of the shock and spring package (under most circumstances). It's also the same scenario where you want to fit the biggest tire/wheel package you can.

barnett468

oh i wasn't referring to yours, just what i have seen others do countless times.



that's my point, it is a band aid, period. the tires hit so you put a band aid on it to fix it. you can try to disguise it by calling it a "performance upgrade" but it is still a b a n d a i d. you like yours the way it is so that's fine but reducing the amount of travel that ford designed into the car is still a band aid.

i can run 20" wide tires and they will never hit if i run 1" of travel.



this is totally different than limiting the travel with a longer bumper or super stiff suspension etc.. lowering a car will simply cause tires that are too wide to hit SOONER.

as i said, do the test i posted. they will hit or they will not, nothing anyone says will change that.
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shelbymustangdan

Thanks guys for the input. To answer 67mustang302, I am running factory (Kelysey-Hayes) disc brakes and the 17x8 rims have a 4.5" back space and zero offset. The rim/tire is a close as you can get to the control arm. Similar to the rears, 17x9s, with 275s and close, but not too close, to the rear leaf springs. And I agree, when I replaced the old rims/tires that were on the car when I bought it, the handling became much better with a wider tire.

If my fenders were rolled, it would not be an issue. Turning clock to clock is more than clear, simply the extreme vertical movement in a few cases when the tires are pointed straight ahead. (such as abnormal dips in the pavement, or steep changes in pavement height, typically at poorly paved intersections) Otherwise, I can run them all day without any issues.

To further work through the problem, I'm going to take the Bilsteins of my 67 coupe which are brand new, and put them on the fastback to see how that effects vertical travel. I'm also going to pull my existing coil springs over the next week or two, take some measurements as requested by a rep at Eaton Detroit Springs, and better understand what coil springs I have in there now. There are no markings or part numbers to identify them. (installed by the previous owner)

Anyway.....thanks again!

Iskwezm

I have 215/45/17's on a 7" wheel with cut coils. It NEVER rubs anything. If I did it again, I would probably put a 225. The front of my car is lower then most so the 215 is a good fit as far as appearance (barely tucks the top of the tire). Im in the process going bigger and wider for SEMA.

67mustang302

I'm not saying that using a stiffer shock/spring combo is the way to solve rubbing issues, but rather a certain shock/spring combo chosen for an application MAY limit travel enough to reduce the incidence of rubbing in most normal driving conditions.

In my case, the setup I have was chosen specifically for handling reasons. As a side effect, there is more limited travel under normal conditions than with more typical setups people run. A lot of it is actually in the shocks. A good shock need only dampen enough to maintain control; and the better a shock gets, the more effectively in will dampen in a narrower range of travel. Most common shocks for Classics are either too severe and over dampen (so called performance shocks that just run a stiffer valving) or are too soft and dampen very poorly (more ride quality oriented shocks). So you either get a crazy stiff ride that often lacks control on rough roads, or you get a soft ride that performs poorly.

Rubbing is easier to avoid if you're going for handling performance, because it becomes an unintended side effect of running a suspension setup that has reduced travel. It doesn't mean that it can't rub, because if you get enough travel in certain conditions rubbing will occur. It just means that it can move from being a problem, to being an occasional annoyance.

As for the OP, he can either roll the fender lip if he's willing to deal with what he has to deal with to do it; or he can try loosening the bolts for the fender and pushing it out farther. The body panel alignment won't be ideal in the case, and isn't what you want to do on a show car, but it might buy additional clearance. Barring that, narrower wheels and tires. 215 or 225 on a 7" wide wheel do fit nicely.

It really comes down to what you want and what you're willing to exchange to get it. For me, I'm willing to accept minor rubbing in a few extreme/limited cases to get additional handling. As long as normal tread wear occurs faster than any wear incurred from rubbing, I'm fine with that. Honestly, if I were made of money, I'd put flares on the front and rear and run 275's front and 285-315's rear depending on what tires are available in what sizes. Though with flares I'd want 0 rubbing under all circumstances, since glass flares aren't nearly as robust as a steel panel and won't take kindly to repeated banging of the tire.