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Offline jays79

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wheels
« on: January 17, 2017, 07:34:58 PM »
Will a +30mm offset on a 15 inch rim work for a 79 pinto?

Offline Wittsend

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Re: wheels
« Reply #1 on: January 18, 2017, 01:19:42 PM »
The +30mm offset is roughly 1-1/4". The 15" wheel is 1-1/2" higher from the center point.  You did not mention the wheel width. Without that you can't determine if, even with the offset stated, the wheel won't hit any portion of the suspension.  You did not mention tire size. Without that it can not be determined if the tire will hit any portion of the suspension or inner body.  Lowering the car (if done) also factors in.

  Frankly even with that information there is a lot of measuring that most people just don't do and thus I doubt you will get an effective reply.  This is why people either purchase or make a wheel/tire simulator out of wood (see images).  The good news is that Pinto wheel openings are VERY generous to larger/wider tires and in most cases brake clearance issues are lessened going to a 15" wheel.  I have temporarily put 225-60-16" tires/wheels off an '88 Turbo Coupe on a stock Pinto and there was only minimal rubbing.  I recall the rear wheels needed to be spaced outward about 1/4" to clear the springs.  But, in this case it was just "test and see".

Your best hope is to state the wheel size, wheel width, offset tires size, - (and possibly if the car is lowered, or not) and see if someone here will have something "similar" and can relay the type of clearances they have.  Otherwise it is like asking if you putting 3/4" hard wood floors in your house if you will hit your head on the top of the doorway.  We can't answer if we don't know how high the door frame is and how tall you are.  And the easiest way to answer that would be to just walk yourself through the doorway - carefully.  This is not the easy answer you probably wanted to hear but if you are planning on spending big for wheels and tires you want to get things right.

Offline jays79

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Re: wheels
« Reply #2 on: January 18, 2017, 05:30:15 PM »
thanks for the reply. the rims are 8 inches wide with a +30mm offset. I have been searching the internet for a set of rims I like for the pinto. so I wouldn't know what size tire to even put on it.  Maybe the better question would be. What is the stock offset of the pinto rim.

Offline Wittsend

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Re: wheels
« Reply #3 on: January 18, 2017, 06:46:16 PM »
So, if the wheels are 8" wide and you add the 1-1/4" (roughly +30mm) then for the wheel itself to avoid hitting the rear spring will need more that 5-1/4" from the face of the brake drum to the leaf spring. And you need more than that, probably an addition 3/16" just to "safely" clear the spring. Then there is tire bulge as the tire expands larger than the wheel itself. This is variable based on the tire size and characteristic s of the manufacturer I'd guess that you need about 1" - but again just a guess.  Lastly there is tire deflection when cornering that will distort the tire towards the spring. Again just a guess there but I'm thinking 1/2".

So, add it all up:  5-1/4" wheel with +300mm offset  + 3/16" spring clearance + 1" tire bulge clearance + 1/2" tire deflection = 6-15/16" or roughly 7".  Pull the rear tire off, place a yardstick across the face of the brake drum and then measure the distance to the leaf spring.  I'm just guessing you will have a tire about 24"-27" in diameter so measure to the spring about 13"off the center of the brake drum - forward and backward. The springs are often not parallel and the distance will be slightly different thus you need to measure at both spots.  If you have 7" or more you should be OK. If not it seems you will have to look elsewhere, consider spacers etc..

 This is for the rear only, the front is a bit harder to figure. But when I used the mentioned 16 T/C wheels it was the rear spring that was the rubbing point.  ALSO, this just relates to the tires and what they may hit going inward.  There can still be rubbing issues with the tire and the wheel well opening going outward.  But like I said the Pinto is generous in that regard and at least makes things hopeful.

Offline jays79

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Re: wheels
« Reply #4 on: January 18, 2017, 08:25:01 PM »
thanks for the info. ill pull the rears off tomorrow. The also offer +20 and +40 in the same rims also

Offline dick1172762

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Re: wheels
« Reply #5 on: January 19, 2017, 08:28:58 AM »
You MUST have 3 3/4" or less back space on a Pinto to clear every thing. Back space is measured from the back edge of the rim to surface of the wheel that touches the brake drum. OR just turn the wheel upside down, lay a 2x4 across the wheel and measure down to the backside of the wheel center. MUST be 3 3/4" or less. 4" will work with .125 (1/8") spacer.
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Offline Wittsend

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Re: wheels
« Reply #6 on: January 19, 2017, 06:28:40 PM »
OK, I get some different numbers (not trying to be argumentative).  The original poster did not state what size 15" tires they planned to run on the 8" wide wheels. However, I'm assuming it would be "around" the 225-60-15"  (roughly 26" diameter) I have mounted on 8" wide wheels - and thus will use then for reference. I briefly ran these wheels/tires on my Pinto and they are visible in my side image.

As I stated above the rear springs are not parallel. The spacing is wider at the rear, therefore bringing the spring closer to the tire - the point of minimal distance. With that in consideration I measured roughly 13" back (half the tire diameter) from the axle center line and got the brake drum face a hair under 6" off the spring at the tightest point. I also got a 5-1/4" backspacing on the wheels I am using for reference.  When I installed the wheel I get right about 1/4" of clearance between the tire and the spring as there is an additional 1/2" tire bulge beyond the wheel edge.  While I would call that minimal I don't recall rubbing and the tire shows no indication of having done so. As I said, I ran them briefly, a long time ago. Also my rear is a Mustang II, 8". I'm assuming all the Pinto/Mustang II rears are the same width. And, again this is rear leaf spring clearance issues. I don't recall any up front issues but it was some time ago. The tires for sure were close to the wheel opening and might have rubbed. Then again they were 225-60-15".

So, at least from the measurements I'm getting I see the following:

1. +30mm (positive offset) moves the rim 1-1/4" closer to the spring off the 4" centerline of a 8" wheel.

2. That would create the same backspacing of 5-1/4" like the wheel I am using for reference.

3.  I have successfully had a 5-1/4" backspacing on a 15" X 8" wheel and 225-60-15" tires. I'd call it close, but I have done it.

It seems at least feasible that the +30mm 15" X 8" wheel will work.  Jays79 YOU need to check (and double check) this for yourself.  You also need to determine if roughly a 1/4" clearance at the spring is sufficient. Even if my numbers are correct it will be very close. BTW, there wasn't much tire clearance with the inner wheel well either.  And, as the car tilts .. . You can use $pacers, but there is the cost and probably anything over 1/8" will require longer $tuds too.

Little things can add up.  I reference 30mm as 1-1/4" but in reality it is a bit smaller at 1.18, not 1.25. That is favorable. Also if you run shorter tires, say a 205-50-15" the tire bulge will be closer to the axle centerline and have a slightly greater gap between the tire and the spring which is also favorable.

Anyway, I don't want to mislead here. So, if my evidence is in error please state so - and why.

Offline jays79

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Re: wheels
« Reply #7 on: January 19, 2017, 06:33:17 PM »
I am looking for a wide wheel and tire combination. Something more on the low profile range. So if any of you have any suggestions on rim size,back spacing and tire size it would greatly be appreciated

Offline dick1172762

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Re: wheels
« Reply #8 on: January 20, 2017, 11:07:10 AM »
I should have stated that my measurement's were for using a 13 inch wheels as most Pinto use. In the front, if you try a wheel with more back space than 3 3/4" you will rub the upper control arms with the wheel. Back wheels are no problem with in reason. Pintos look best with the same dish on all 4 wheels.(or so I think). Again this is for 13 inch wheels.
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