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5/12/2013 3:49 PM  #1


why 17x7 wheels instead of 17x8?

I have a 65 coupe that'll be getting a one inch drop, shekby drop, roller bearing upper and lower control arms and 4.5 mid eye leaf springs.  Previously before the board was converted over, 17x7's were recommended over 17x8 for better performance and less chance of clearance issues.

I'm curious though, why would 17x7's be better?  The engine I'll be running dyno'd just shy of 250rwhp in the previous car I had it in.  Will 17x7's be too small for me?  Will 17x8's allow me to obtain better traction in the corners?

 

5/12/2013 5:48 PM  #2


Re: why 17x7 wheels instead of 17x8?

what brakes are you running now?
what wheels do you have or, are you considering?

 

5/12/2013 6:22 PM  #3


Re: why 17x7 wheels instead of 17x8?

The idea is that a wheel that actually fits the car and does not cause tires to rub will allow you to drive your car in a more high performance manner without fear of killing yourself when you shred a tire at 80 MPH going down the highway.


Money you enjoy wasting is NOT wasted money... unless your wife finds out.
 

5/12/2013 9:05 PM  #4


Re: why 17x7 wheels instead of 17x8?

MustangSteve wrote:

The idea is that a wheel that actually fits the car and does not cause tires to rub will allow you to drive your car in a more high performance manner without fear of killing yourself when you shred a tire at 80 MPH going down the highway.

That's a big DUH on my part.  That makes perfect sense. Is a 225/45 the widest I'll be able to go on a 17x7 without running into sidewall issues while cornering?  Will 225's be able to give me adequate traction around the corners or would I be better served to clearance my fenders to fit a 17x8 with 245/45's?


josh-kebob wrote:

what brakes are you running now?
what wheels do you have or, are you considering?

I'll be running 13 inch cobra brakes up front with the matching cobra discs in the rear.  I just ordered a set of 17x7 torq thrust m wheels with 4 inch back spacing but I'm trying to determine if I'll regret not going with 17x8's

     Thread Starter
 

5/12/2013 11:32 PM  #5


Re: why 17x7 wheels instead of 17x8?

Brake caliper clearance is problematic with the wheels you have chose.  You may wind up needing a spacer in the front.  Find out by mounting a wheel on the car BEFORE you put a tire on in case you have to return them.  They won't take them back after you put rubber on them.

i have 17x8 on my car with 4 3/4" back spacing and Yokohama 235/45/17 all around.   It doesn't rub, but I did roll the rear fender lip and massaged the front of the inner wheelhouse (it rubbed in those two spots when I had16x  7" with 4 1/2" backspacing wheels).

The big advantage of 7" wheels is they are easier to fit on the 64-66 cars.  IMO this is why they a popular.  They don't look that different.  For a street car I think they might be the best option (certainly they are the most foolproof).

Last edited by CraigMBA (5/12/2013 11:35 PM)

 

5/12/2013 11:34 PM  #6


Re: why 17x7 wheels instead of 17x8?

I'm running a 235/45/17X7 on the front of my 68 with no spacers and no rubbing. The wheels are off a 2004 Mustang and they were narrowed from 8 to 7 inches.


68 coupe - 351W, 4R70W, 9" 3.25 -- 65 convertible - 289 4v, C4, 8" 3.00
 

5/13/2013 7:05 AM  #7


Re: why 17x7 wheels instead of 17x8?

Torque Thrust M wheels clear cobra brakes just fine.  I have 235x45/17 on the front of my 66 with 17x7 wheels.  You will need to roll your fenders even with the 17x7 wheel, using the M wheels.  Mine have 4.72" backspacing and clear everything just fine.

Tire grip will not be your limiting fator in cornering.


Money you enjoy wasting is NOT wasted money... unless your wife finds out.
 

5/13/2013 2:44 PM  #8


Re: why 17x7 wheels instead of 17x8?

I misread them as torque thrust II.  My mistake Steve.

 

5/14/2013 1:16 PM  #9


Re: why 17x7 wheels instead of 17x8?

MustangSteve wrote:

Torque Thrust M wheels clear cobra brakes just fine.  I have 235x45/17 on the front of my 66 with 17x7 wheels.  You will need to roll your fenders even with the 17x7 wheel, using the M wheels.  Mine have 4.72" backspacing and clear everything just fine.

Tire grip will not be your limiting fator in cornering.

Thank you for the input, I appreciate it.   Most of my concern comes from wondering if I'll have too much power for the amount of grip that 225 or 235 tires can provide, or if I'll have to feather the throttle around the corner to avoid swinging the back end around.
 

Last edited by 50 Proof (5/14/2013 1:19 PM)

     Thread Starter
 

5/14/2013 7:47 PM  #10


Re: why 17x7 wheels instead of 17x8?

IS this a race car or a street car?  It cannot be BOTH and do either one very well.  You have to decide where it will NORMALLY be used and build it to do that the best it can be.  If it is a race car only, then you have lots more mods to do before it begins to drive how you think it should.  Be realistic.  Which is it?


Money you enjoy wasting is NOT wasted money... unless your wife finds out.
 

5/15/2013 7:40 AM  #11


Re: why 17x7 wheels instead of 17x8?

MustangSteve wrote:

IS this a race car or a street car?  It cannot be BOTH and do either one very well.  You have to decide where it will NORMALLY be used and build it to do that the best it can be.  If it is a race car only, then you have lots more mods to do before it begins to drive how you think it should.  Be realistic.  Which is it?

 
I appreciate your honesty and bluntness.  Having thought about your question over night, the reality is I won't have the time capacity to race this car on a track as frequently as I would like to.  It would be more reasonable to target it to be a street car.  I will get more enjoyment by being able to drive it on the street as a street car than to build a race car and get frustrated by my lack of time to be able to race it.  That is what I will need to keep reminding myself of.

     Thread Starter
 

5/15/2013 10:48 AM  #12


Re: why 17x7 wheels instead of 17x8?

Sometimes I have to whoop out the TOUGH LOVE questions.

For a car normally driven on the street, it is much more important that the wheels do not scrape the fenders than it is to have the widest possible tire.


Money you enjoy wasting is NOT wasted money... unless your wife finds out.
 

5/15/2013 11:27 AM  #13


Re: why 17x7 wheels instead of 17x8?

Steve, I have the 06 16x7 with 225x55 on the back of my 66. Looks like a lot of room in the wheel wells. Could I safely upgrade to 235. I have the 1.25" spacers. Street car and track days once a year


66 coupe 289 Weiand T5 3.40 disc brakes progressive coils Bilstein 4.5 leaf mid-eyes 1" front sway bar 16" wheels
 

5/15/2013 12:00 PM  #14


Re: why 17x7 wheels instead of 17x8?

ponyboy, since you already have an existing tire, it is simple math to determine if something else will fit.  Got to tirerack.com.  Look up the tire you now have on the car.  Click on the tire SPECS tab and it will gove you diameter and cross-section and tread width for that tire.  Then call up the new size and compare the numbers.  Remember, a tire that is 1" taller only extends 1/2" out farther from center.  Get your tape measure and check the clearance you have.  Allow for the extensive sideways and angular movement the axle will see when going in and out of steep angled driveways.


Money you enjoy wasting is NOT wasted money... unless your wife finds out.
 

5/15/2013 12:19 PM  #15


Re: why 17x7 wheels instead of 17x8?

http://www.rimsntires.com/specs.jsp
This tool works well to compare tire/wheel combos.

 

5/15/2013 2:25 PM  #16


Re: why 17x7 wheels instead of 17x8?

17x7 in the front with 225/45/17
17x8 on the rear with 245/45/17
Staggered wheels aand staggered tires
My 15 in TTII's are staggered 7 front, 8 rear


If it ain't broke, I haven't modified it Yet
 

5/15/2013 5:48 PM  #17


Re: why 17x7 wheels instead of 17x8?

MustangSteve wrote:

Sometimes I have to whoop out the TOUGH LOVE questions.

For a car normally driven on the street, it is much more important that the wheels do not scrape the fenders than it is to have the widest possible tire.

For a track car, it's even more important!

 

5/17/2013 1:31 PM  #18


Re: why 17x7 wheels instead of 17x8?

 

5/17/2013 1:35 PM  #19


Re: why 17x7 wheels instead of 17x8?



This car has either 16x8 or 17" wheels and stock wheel houses (class rules only allow for "stock" style suspension and minimal body mods).  it has 4.5 leaf springs and has to be pretty street able because its an endurance race car that runs on public roads.

That look like enough cornering grip for you?

 

 

5/17/2013 3:25 PM  #20


Re: why 17x7 wheels instead of 17x8?

I don't see any air under that passenger front tire 


Nick - 65FB 410C AOD 'D.T.' - 67FB 347 T5 'Cruiser' - 68FB 408W T5 'Brute'
 

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