My rear tires are rubbing!
#1
Hello all!  I just put brand new rubber on 15" by 8" wide rims.   Back:  255, 60's.  Front:  235, 60's. 

The rear tires hit the wheel well every time I go over a bump.  There are rubbing marks almost 3 inches down the side of the tire!  I thought it was just the lip of the wheel well it was hitting, but I see faint rubbing marks on the body farther up, so even if I hypothetically ground the lip off, it would still rub (not as bad) farther up.

So my question is suspension VS tires.

Should I get 245's?  Would that solve it or is that too little?  The marks are almost 3 inches down the side like I mentioned.  I'm thinking maybe the rims have the wrong backspacing as well, which would cause them to sit out farther from the car.

Should I mess with the suspension?  I know nothing about suspension, and it looks like the last guy before me upgraded it.  It is STIFF, and when I jack up the car, the tires basically don't move... 

Thanks.  -Jonner B
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#2
First thing to check is the clearance between the back of the tire, and the leaf spring. To see how much you can go back. There's probably a little room back there, but with 255's I wouldn't think there would be a lot, if you have a couple inches you might be able to change the back spacing, I would still like to have a solid inch between the tire, and the spring for clearance. If you don't have the clearance? You'll either have to go to 245's maybe even 235's , or raise the rear suspension, with shackles, air shocks, or rearched springs. None of which, I would recommend. The Mach1 doesn't have extremely large wheel wells, so a lot of measuring will be needed to correct your problem. Mister 4X4 has about the largest tires I've seen a a Mach1, I was thinking they were 245's. Hopefully he'll see your post, and chime in. Hope it helps 

JTS
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#3
P255 x 60 seems like a big tire to fit into a Mustang wheel well but I am sure it has been done.  In regards to modifying your suspension to accommodate a taller tire you have to consider how prefer the stance of your car.  Some people like their car jacked up in the back so it looks like your driving down hill and other like it level and some, like myself, like the Mustangs to squat in the back.  It's all personal preference.  I decided to go with a smaller tire to achieve the stance I wanted.

If your tire is hitting the inside of the wheel well it sounds like you will need a smaller tire or you can compensate with changing/modifying your suspension to accommodate the taller tire .  If it is rubbing the lip of quarter panel then most likely you will need a deeper backspace on the wheel.

As JTS said hopefully Mister 4x4 will chime in. If my memory serves me correctly he has a rather tall tire on his car.

Mike

.
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#4
(09-28-2019, 07:40 AM)JTS71 Mach1 Wrote: First thing to check is the clearance between the back of the tire, and the leaf spring. To see how much you can go back. There's probably a little room back there, but with 255's I wouldn't think there would be a lot, if you have a couple inches you might be able to change the back spacing, I would still like to have a solid inch between the tire, and the spring for clearance. If you don't have the clearance? You'll either have to go to 245's maybe even 235's , or raise the rear suspension, with shackles, air shocks, or rearched springs. None of which, I would recommend. The Mach1 doesn't have extremely large wheel wells, so a lot of measuring will be needed to correct your problem. Mister 4X4 has about the largest tires I've seen a a Mach1, I was thinking they were 245's. Hopefully he'll see your post, and chime in. Hope it helps 

JTS

Thanks JTS.  Yeah I think there is a bit of spacing back three, but I thought the backspacing would be fine.  I believe its 3.62.  I already have the tires and rims, (which I thought I did enough research)  So to get different rims and tires would obviously not be desirable.  I bent in the inner lip enough that I think it will help, without it being visible.  I'm hoping that will solve it.  If not, that paired with smaller rubber might be just enough.  Like I said, its only bad over bumps, so I just need to gain a little bit of room.  I was going to test my work today but its raining.  

Side note, I just need to put the decals on and then I will post lots of pictures of the final product!

-Jonner B
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#5
(09-28-2019, 09:49 AM)Mustangmike Wrote: P255 x 60 seems like a big tire to fit into a Mustang wheel well but I am sure it has been done.  In regards to modifying your suspension to accommodate a taller tire you have to consider how prefer the stance of your car.  Some people like their car jacked up in the back so it looks like your driving down hill and other like it level and some, like myself, like the Mustangs to squat in the back.  It's all personal preference.  I decided to go with a smaller tire to achieve the stance I wanted.

If your tire is hitting the inside of the wheel well it sounds like you will need a smaller tire or you can compensate with changing/modifying your suspension to accommodate the taller tire .  If it is rubbing the lip of quarter panel then most likely you will need a deeper backspace on the wheel.

As JTS said hopefully Mister 4x4 will chime in. If my memory serves me correctly he has a rather tall tire on his car.

Mike

.
Hey Mike.  Yeah it does, but my logic was that it would be fine because that's the size of the rubber when I bought the car!  The rims were an odd 7.5 inch wide, but the rubber was the exact same as what I put on.  Going on that logic I thought I would be fine, but now I see the difference in backspacing is what got me.  Yeah I thought of getting different backspacing, but that would mean new rims all around which is a last resort in my mind.  We'll see.  Thanks!

-Jonner B
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#6
Hey Jon, Take a Look at  Eastwood.com  They make a fender lip rolling machine/tool that bolts to the axle/hub, and it will roll the inner lip usually resulting in about 3/4" additional clearance. Having bent the lip as you said, you may have already got that much. Just some more ideas. Hope you get it figured out. 

JTS
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#7
(09-29-2019, 05:33 AM)HJonner B Wrote:
(09-28-2019, 09:49 AM)Mustangmike Wrote: P255 x 60 seems like a big tire to fit into a Mustang wheel well but I am sure it has been done.  In regards to modifying your suspension to accommodate a taller tire you have to consider how prefer the stance of your car.  Some people like their car jacked up in the back so it looks like your driving down hill and other like it level and some, like myself, like the Mustangs to squat in the back.  It's all personal preference.  I decided to go with a smaller tire to achieve the stance I wanted.

If your tire is hitting the inside of the wheel well it sounds like you will need a smaller tire or you can compensate with changing/modifying your suspension to accommodate the taller tire .  If it is rubbing the lip of quarter panel then most likely you will need a deeper backspace on the wheel.

As JTS said hopefully Mister 4x4 will chime in. If my memory serves me correctly he has a rather tall tire on his car.

Mike

.
Hey Mike.  Yeah it does, but my logic was that it would be fine because that's the size of the rubber when I bought the car!  The rims were an odd 7.5 inch wide, but the rubber was the exact same as what I put on.  Going on that logic I thought I would be fine, but now I see the difference in backspacing is what got me.  Yeah I thought of getting different backspacing, but that would mean new rims all around which is a last resort in my mind.  We'll see.  Thanks!

-Jonner B
Hey Jonner,

It sounds like an backspace issue.  3.62 BS seems kind of shallow for 255 tires. I am running a 5 inch BS on my car with 255 with no clearance issues.  If you have plenty of clearance between the backside of your wheel and the leaf springs then look for a wheel with a deeper backspace like 4 or 4.5 inches. 
Here is a picture of my P255 tires on a wheel with a 5 inch backspace.  Plenty of room.


Attached Files Image(s)
   
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#8
(09-30-2019, 01:45 AM)Mustangmike Wrote:
(09-29-2019, 05:33 AM)HJonner B Wrote:
(09-28-2019, 09:49 AM)Mustangmike Wrote: P255 x 60 seems like a big tire to fit into a Mustang wheel well but I am sure it has been done.  In regards to modifying your suspension to accommodate a taller tire you have to consider how prefer the stance of your car.  Some people like their car jacked up in the back so it looks like your driving down hill and other like it level and some, like myself, like the Mustangs to squat in the back.  It's all personal preference.  I decided to go with a smaller tire to achieve the stance I wanted.

If your tire is hitting the inside of the wheel well it sounds like you will need a smaller tire or you can compensate with changing/modifying your suspension to accommodate the taller tire .  If it is rubbing the lip of quarter panel then most likely you will need a deeper backspace on the wheel.

As JTS said hopefully Mister 4x4 will chime in. If my memory serves me correctly he has a rather tall tire on his car.

Mike

.
Hey Mike.  Yeah it does, but my logic was that it would be fine because that's the size of the rubber when I bought the car!  The rims were an odd 7.5 inch wide, but the rubber was the exact same as what I put on.  Going on that logic I thought I would be fine, but now I see the difference in backspacing is what got me.  Yeah I thought of getting different backspacing, but that would mean new rims all around which is a last resort in my mind.  We'll see.  Thanks!

-Jonner B
Hey Jonner,

It sounds like an backspace issue.  3.62 BS seems kind of shallow for 255 tires. I am running a 5 inch BS on my car with 255 with no clearance issues.  If you have plenty of clearance between the backside of your wheel and the leaf springs then look for a wheel with a deeper backspace like 4 or 4.5 inches. 
Here is a picture of my P255 tires on a wheel with a 5 inch backspace.  Plenty of room.
Yeah I guess you are right.  It seemed like all the rim options I looked at were 3.6 however, and it looked like that was standard.  I don't believe the rim I chose came in any different BS, so I would have to get all new rims.  Dang.  I don't know.  Decisions Decisions.  Guess I'll have to figure something out!  Thanks for now!
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#9
Wow - 3.6" of backspacing on an 8" rim shouldn't have pushed out too far.  That's just under halfway on an 8" rim, which I'm just under halfway on a 10" rim with no rubbing.  Totally confused here.

So, in your other thread you mentioned that you cured the rubbing - what did you do?  I apologize for not chiming in earlier... I had a friend in from out of town and we were playing with getting my Jeep running all weekend (he just left this morning to head back to Phoenix).

Actually, my tires aren't any taller than stock - 26.6".  They're 245/60R15s on 15x8 up front, and 295/50R15s on 15x10 (5.25" BS) out back.
Reply
#10
Wow Eric those are even bigger then I thought! I sure didn't know they were 295's. Nice Job getting them to fit. 

JTS
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