What's the widest tire

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Sadittyf

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1973 mach1 building a custom/street car out of it plans are 69 fastback quarter panels, TCI G-link, reverse valve body c6, and a 521 on e85
So I'm curious to what is the widest rear tire you guys have fitted on your cars with out tubing or back halfing ether as well as wheel specs you used to reach the width you guys have pics will help as well thanks guys

 
So I'm curious to what is the widest rear tire you guys have fitted on your cars with out tubing or back halfing ether as well as wheel specs you used to reach the width you guys have pics will help as well thanks guys
I'm running 285/40/18 Nittos on 18x9 US Bandit rims. 5.25" backspace with plenty of extra space to go wider with the right backspacing.

 
... And here's why the right backspacing is important.

These are 295/50R15s on 15x10 Cragar S/Ss with 4.25" of backspacing.
Frankcarshow6.jpg

Frankcarshow5.jpg

While they look really cool just sitting there...
Frankenstang2014.jpg

... they scrub the outer lip on just about everything - even with the 5-leaf spring pack, new shocks and bushings. I want a just little bit of boost in the back (the old school look works for me) so I'll be installing some factory-style 1-inch shackles, but the only way to make sure there are no rubs is to change the backspacing to get them tucked in a little tighter. Cragars (and most other rims) can be ordered with custom backspacing and/or offsets, so that's the way to go when it comes to stuffing the big rubber under there.

Some of the other guys have similar set-ups with better backspacing and report no issues. I think 5" of backspacing is about the least amount you want with 295s on 10" rims, but 5.25" or even 5.5" would be better. Another guy has 6.5" on his, and they fully tuck, but he said he had to modify the inner wheel houses to clear.

The fronts are 245/60R15s on 15x8s, BTW. No issues whatsoever.

Hope this "example of what not to do" helps someone avoid an expensive mistake in the future. :cool:
 
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Thank you guys a lot I have a huge thing for perfect near perfect fitment on wheels and tires I like to fit the max width I can with out to much rubbing at full lock I love big wide tires my goal is after I get the 69 quarter panels mounted I hope to run a 325 rear tire but I'm hoping with the right backspacing and the extra width I get from the quarter panels I hope I cross honestly get a 355 tucked nicely in the rear

 
Some of the other guys have similar set-ups with better backspacing and report no issues. I think 5" of backspacing is about the least amount you want with 295s on 10" rims, but 5.25" or even 5.5" would be better. Another guy has 6.5" on his, and they fully tuck, but he said he had to modify the inner wheel houses to clear.

The fronts are 245/60R15s on 15x8s, BTW. No issues whatsoever.
I am subscribing to this thread. This is one of my upcoming expenses for next year. Excellent information Eric. Second response of the day that comes at the right time for me. 295s and 245s on 15s look like a great combination to have.

 
Modifying the inner fenders(against the frame rails) can be done with a hammer and about two minutes per side. Not much, but I felt the need to mention it.

Magnum500s011.jpg


 
I was pretty sure that's what you said you'd done, but I figured you'd chime in with a pic of your awesome car and its big ol' fat meats. ::thumb::

 
It'll be a week or so before I get them and a few more days before they are mounted, but I intend to fit M&H 325-45-17's to the rear of my car. This will not only be wider but a 28" tall tire as opposed to the current 26" height.

And for shits and giggles, I now have my 255's on the front of the car. I've got about a 1/2 clearance to the upper balljoint and no rubbing at all.

With manual steering, parking lots are now my number 2 sworn enemy!

 
Mike, if you can provide a step by step for a newbie like me on how you rolled the inner fender I would appreciate it. I am hoping to be able to fully tuck in 295/50-15s in the back fender wells with custom backspace rims. Really like the look you have there.

Also not to go to far off topic, but if anyone has an opinion on the trade offs of handling versus front end wear and tear with front tire size I would be interested. Thanks,

Scott

 
I currently have 295s on the rear and 255s on the front on 18" wheels. No rubbing.

I should've tried 315s on the rear and 275s up front. I believe 315s on the rear can be easily done but I'm not sure of 275s up front. Maybe if one would choose a tire brand in which the cross section runs narrower than other brands.

 
Modifying the inner fenders(against the frame rails) can be done with a hammer and about two minutes per side. Not much, but I felt the need to mention it.

Magnum500s011.jpg
Could you describe how you delicately smashed in your inner fenders (against the frame rails), not to be confused with rolling the fender lips? As in how much "modification" was required? I also think your setup looks sweet but at what cost.(how's the inner fender look)

Are the rears 295/ 50 R15's on rims w/ 6.5" backspacing? Just clarifying...

Have any pics of the altered inner panels? I also want to get as much rubber, fully underneath, as possible, w/o any rubbing...

Thanks, Eric



I currently have 295s on the rear and 255s on the front on 18" wheels. No rubbing.

I should've tried 315s on the rear and 275s up front. I believe 315s on the rear can be easily done but I'm not sure of 275s up front. Maybe if one would choose a tire brand in which the cross section runs narrower than other brands.
What's your rear wheel offset?



I've fit 315-35-17's on 17x10.5's with 6.66 inches of backspacing and I haven't even rolled the fender lips. I'm , running 5 leaf 200 pound leaf springs in back.
Jeff, did you also have to, shall we say, "finesse" those 6.66"ers in with a hammer...?

 
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I did a little finessing but not much. The biggest thing I did was to trim the lip off the front of the bump stop and lightly flatten out the inner panel. It would only be noticeable to someone that was looking for it. Relocating the fuel line is also a good idea, but I haven't bothered with that yet.

Next week when I put 28" tall 325's in, I'll be glad to post back how the clearances are, but even having lowered the car an inch I think I'll be fine.

 
I did a little finessing but not much. The biggest thing I did was to trim the lip off the front of the bump stop and lightly flatten out the inner panel. It would only be noticeable to someone that was looking for it. Relocating the fuel line is also a good idea, but I haven't bothered with that yet.

Next week when I put 28" tall 325's in, I'll be glad to post back how the clearances are, but even having lowered the car an inch I think I'll be fine.
Please do! Thanks!

 
Not much too it. Use a BFH to pound in the inner fender sheet metal until its flush with the frame rail. Maybe I moved it 1/2"-3/4".

Even after this the tire is still quite close. I can not fit my fingers between the tire and inner fender. Hopefully your axle is perfectly centered like mine was and I recommend heavy duty shackles to keep the leaf springs as centered as possible during cornering. It's been 16 years now and rubbing is of no concern to me on my car. Some people's comfort margins are different than mine so that is why I felt the need to mention it. And this would probably not be a good option if you plan on road racing the car.

image5.jpg

 
Not much too it. Use a BFH to pound in the inner fender sheet metal until its flush with the frame rail. Maybe I moved it 1/2"-3/4".

Even after this the tire is still quite close. I can not fit my fingers between the tire and inner fender. Hopefully your axle is perfectly centered like mine was and I recommend heavy duty shackles to keep the leaf springs as centered as possible during cornering. It's been 16 years now and rubbing is of no concern to me on my car. Some people's comfort margins are different than mine so that is why I felt the need to mention it. And this would probably not be a good option if you plan on road racing the car.
Mike, thanks for posting the pics and describing the tolerances your wheel/tire combo gave you. Could you clarify what exactly the wheel/tire combo is...?is it as Eric (mister4x4) eluded to...295/ 50 R15's on what width rims w/ 6.5" backspacing? Your input, pics and description are great information but only relevant to a specific tire/wheel offset. I appreciate your help! What brand of tires are they? Thanks.

Eric



... And here's why the right backspacing is important.

These are 295/50R15s on 15x10 Cragar S/Ss with 4.25" of backspacing.

attachment.php


While they look really cool just sitting there...

attachment.php


attachment.php


... they scrub the outer lip on just about everything - even with the 5-leaf spring pack, new shocks and bushings. I want a just little bit of boost in the back (the old school look works for me) so I'll be installing some factory-style 1-inch shackles, but the only way to make sure there are no rubs is to change the backspacing to get them tucked in a little tighter. Cragars (and most other rims) can be ordered with custom backspacing and/or offsets, so that's the way to go when it comes to stuffing the big rubber under there.

Some of the other guys have similar set-ups with better backspacing and report no issues. I think 5" of backspacing is about the least amount you want with 295s on 10" rims, but 5.25" or even 5.5" would be better. Another guy has 6.5" on his, and they fully tuck, but he said he had to modify the inner wheel houses to clear.

The fronts are 245/60R15s on 15x8s, BTW. No issues whatsoever.

Hope this "example of what not to do" helps someone avoid an expensive mistake in the future. :cool:
 
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I did a little finessing but not much. The biggest thing I did was to trim the lip off the front of the bump stop and lightly flatten out the inner panel. It would only be noticeable to someone that was looking for it. Relocating the fuel line is also a good idea, but I haven't bothered with that yet.

Next week when I put 28" tall 325's in, I'll be glad to post back how the clearances are, but even having lowered the car an inch I think I'll be fine.
Jeff, I like your thinking on the 325/ 45 R17 tire's height. 28.5" tall, 12.8" wide. My 275/60 R15's are 28" tall. I like the proportions of tire height to wheel well opening size, as the margin is the same all the way around the tire.

20151024_144857.jpg

As tempting as the additional width is...

The math presented here in this thread:




Eric (Mister4x4) 15 x 10" wheel with 4.25" backspacing. 295/ 50 R15 tire- 26.6" tall, 11.6" wide (tire out too far-could move in 1"-2")

Mike (MeZapu) 15 x 10"? wheel with 6.5" backspacing. 295/ 50 R15 tire- 26.6" tall, 11.6" wide (Modified inner fender w/ BFH, inward 1/2"-3/4", flush to frame rail. Cannot fit finger in between tire and inner fender- probably 3/8"±? space---looks great, a lil' tight.)

Mike's setup seems closer to perfection than Eric's (same tire width of 11.6") as his wheel offset move the tires inward 2-1/4". If we were looking to customize/optimize an offset for this wheel/tire combo, I'm liking maybe 1/2"-1" less offset than Mike's, which would net us 5-1/2" without the BFH mod or 5-3/4" to 6" with the BFH mod. I'd probably end up going with the 6" backspace and the hammer. This would keep me a lil' further from both the "modified" inner fender (Mike's) and the outer fender lip.(Eric's)

Jeff, I hope your new 12.8" wide tire fits but the math says the tire will be 5/8" wider toward the inner fender. (1/2 of 1.2") Plus your 6.66" backspace wheel is also 1/8"- 3/16" more inward than Mike's. If Mike can't fit his finger in between his "modified" inner fender and his tire, how will 5/8"- 9/16" more tire fit? There's only one way to find out, as there are differences between brands and your wheel is 1/2" wider (10-1/2" as opposed to 10") which will create less of a sidewall bulge. Is there a 28" tall tire that is 11.6" wide?... as that seems ideal. My 275/60 R15's are 28" tall and are 10.8" (10- 7/8") wide. (I don't know my offset)

 


20151024_145143 - Copy.jpg

 
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