Increasing rim & tire size - Impala Tech
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post #1 of 12 (permalink) Old 04-20-2011, 10:54 PM Thread Starter
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Increasing rim & tire size

On my '67 impala, i have the stock 14 inch rims with bias ply tires. I am thinking of upgrading to radials and cragar s/s rims but i was wondering if i could put 15 inch rims on and not have a problem with the tire rubbing on the wheel well when i turn. Also, i was thinking on making both the rear and front tires wider but the rear tires being wider than the front. How thick could i go on the front and rear tires without worrying about rubbing?
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post #2 of 12 (permalink) Old 04-21-2011, 12:30 AM
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On my 68' I run 15X8's on all 4 corners with a b/s of 4"( your factory Corvette's). You can go 4.25" on the front but you'll have to run a narrower tire, something in a 70 series.
I'm running 235.60.15 on front and 245.60.15 out back. The fronts look a little too fat for me so I'll be dropping down to a 70 series also.
Check out my pics. and you will see what I mean.
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post #3 of 12 (permalink) Old 04-23-2011, 09:09 PM
 
 
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dude i got a 65 impala and i just put 20`s on mine 225/35/20 looks great, that wheel base is high enough for like 24`s
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post #4 of 12 (permalink) Old 04-24-2011, 02:37 PM
BA.
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Quote:
Originally Posted by 68imp View Post
On my 68' I run 15X8's on all 4 corners with a b/s of 4"( your factory Corvette's). You can go 4.25" on the front but you'll have to run a narrower tire, something in a 70 series.
I'm running 235.60.15 on front and 245.60.15 out back. The fronts look a little too fat for me so I'll be dropping down to a 70 series also.
Check out my pics. and you will see what I mean.

I'm confused John, "dropping down to a 70 series"... that would be a bigger sidewall than the current 60 series you have.
I looked for pics of your ride but couldn't find any anywhere. Help?

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #5 of 12 (permalink) Old 04-24-2011, 07:55 PM
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hi guys I have a 66 SS and am running 225 15 60 on the front and 235 60 15 on the back all 15 x7 rims soon well change the back to 275 60 15 and use a 15 x8 with 4.5 back space now that looks nice.
if you use a 225 on the front its a nice size tyre and look great on the road. old cars look good with big tyres not 18 or 20'' rims but every one is different so thats it cheers
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post #6 of 12 (permalink) Old 04-24-2011, 08:36 PM
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Allan, Nothing in concrete and the tire's on now is basically to keep it off the ground but Per BFGoodrich specs. 255.60 = 27" tall and a 10" footprint; a 215.70 = 27" tall and a 9" footprint. That's what I was going by and no visual on how they would look installed.
The 235.60 up front have too much sidewall roll for me and I'm just looking for something in the same height with less cross section up front. But I can also leave as is and tweak the ratio size a little.


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post #7 of 12 (permalink) Old 04-25-2011, 11:06 AM
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How wide are you really thinking about? I think 68imp's combo of 235s & 245s on 15x8 rims would be good unless you want to go super wide.

I have 15x8 Cragar SS's on the front of my 66. 2.5" backspacing and 245/60R15 tires. They rub on the corner of the fender well when I turn too fast, which I think is due to the 40 year old bushings I have yet to replace. At low speeds they are fine. If you went with either less backspacing or a 235 then I don't think you would have an issue at all but you may run into it with that combo.

I have 15x10s with 4.25" backspacing and 295/55R15 tires on the rear if you want to go real wide. I had to trim off the little metal lip inside the wheel well to get them to fit, but they do fit. Anything less than that should fit without a problem since you have quite a bit of clearance back there.

66' Biscayne 4-door
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post #8 of 12 (permalink) Old 05-08-2011, 02:02 AM Thread Starter
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What do you guys think would look the best on the front and back because i want to do two different sizes. Would I notice the width difference of 15x8's in the rear and 15x7's in the front or do i need to go wider or skinner on either?
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post #9 of 12 (permalink) Old 05-08-2011, 09:52 AM
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With my '85 I want it to look as close to a stock four door sedan that was rescued from off the back a salvage truck as I can get it to look. But I really do need as big a tire as I can stuff under the wheel well for traction in the back; because unlike looking like a drag car, my car actually is a drag car that has to be able to put close to a thousand horsepower on the ground. First clue: there isn't a street tire made that can do that; so I have to use a slick. I try and use a DOT slick because it is street driven (won't pass safety tech at the track) and I am trying to pass it off as a stock car (wolf in sheep's clothing) so a set of 23 inch wide GoodYear drag slicks would scare away any potential rivals.

The reason race cars have big and littles is the smallest tire that you can find goes up front to reduce rolling friction by inflating it to maximum pressure. And the widest tire that you can find goes on the back running as low a pressure as you can and still drive the car in a straight line without crashing it. I assume by this talk of unequal tire and wheel size you are trying to make your car look like a drag race car; otherwise you would have the same size tire on all four corners of the car to maximize control and traction.

Road race cars use wider that stock tires to improve traction as all suspension begins and ends with planting the biggest patch of rubber that you can at all four corners and keeping it flat on the ground no matter what you are asking the car to do. So a NASCAR or SCCA car has 10, 12, or 14 inch wide rubber racing tires fore and aft to be able to apply brakes (drag cars do not have brakes on the front axle), and to be able to turn a corner (drag cars only drive in a straight line for a short distance).

So I am still confused on why you want different sized wheels and tires on a stock car (of course shinny fresh paint and waxing a car is something I never do either, so I guess I'm just different).

Big Dave
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post #10 of 12 (permalink) Old 05-09-2011, 09:49 AM
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On my 67 Impala I run a 215/75R15 front tire on a 15x6 wheel with 3-1/2 B.S.
On the rear I run a 275/60R15 tire on a 15x8 wheel with 4-1/4 B.S. The wheels are
Wheel Vintiques chrome rallys, they fit good & look good.
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post #11 of 12 (permalink) Old 01-31-2012, 11:24 PM
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my 68 is lowered a couple of inches and sitting on 20 inch wheels with a 225 35 20 and it doesn't rub at all,the overall diameter of my tire is 28 3/4 inches, you will be fine with any properly selected 15" combo
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post #12 of 12 (permalink) Old 02-02-2012, 01:06 PM
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Quote:
Originally Posted by Big Dave View Post
With my '85 I want it to look as close to a stock four door sedan that was rescued from off the back a salvage truck as I can get it to look. But I really do need as big a tire as I can stuff under the wheel well for traction in the back; because unlike looking like a drag car, my car actually is a drag car that has to be able to put close to a thousand horsepower on the ground. First clue: there isn't a street tire made that can do that; so I have to use a slick. I try and use a DOT slick because it is street driven (won't pass safety tech at the track) and I am trying to pass it off as a stock car (wolf in sheep's clothing) so a set of 23 inch wide GoodYear drag slicks would scare away any potential rivals.

The reason race cars have big and littles is the smallest tire that you can find goes up front to reduce rolling friction by inflating it to maximum pressure. And the widest tire that you can find goes on the back running as low a pressure as you can and still drive the car in a straight line without crashing it. I assume by this talk of unequal tire and wheel size you are trying to make your car look like a drag race car; otherwise you would have the same size tire on all four corners of the car to maximize control and traction.

Road race cars use wider that stock tires to improve traction as all suspension begins and ends with planting the biggest patch of rubber that you can at all four corners and keeping it flat on the ground no matter what you are asking the car to do. So a NASCAR or SCCA car has 10, 12, or 14 inch wide rubber racing tires fore and aft to be able to apply brakes (drag cars do not have brakes on the front axle), and to be able to turn a corner (drag cars only drive in a straight line for a short distance).

So I am still confused on why you want different sized wheels and tires on a stock car (of course shinny fresh paint and waxing a car is something I never do either, so I guess I'm just different).

Big Dave
The looks of bigs and littles on a street car looks much better (having the same tire front and back looks goofy on some cars). Personally I like to fill the wheelwell in the back, but that same tire size in the front would look goofy, so I go with smaller tires on the front (which also makes it easier to steer). It's a more current look, and looks much better.
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