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Question on tread width.

13K views 16 replies 7 participants last post by  RWENUTS 
#1 ·
Looking to put a Mustang II IFS in a 1958 Morris Minor. The Morris Minor total width is 61" . The Mustang II Tread width is 55". When they say tread width do they mean the inside edge of the tire or the out side edge of the tire?

Thanks dan
 
#2 ·
impalaman63 said:
Looking to put a Mustang II IFS in a 1958 Morris Minor. The Morris Minor total width is 61" . The Mustang II Tread width is 55". When they say tread width do they mean the inside edge of the tire or the out side edge of the tire?

Thanks dan
Vehicle specs read center of front tire to center of front tire...... which is affected by wheel offset/backspace.
In your situation you should be concerned with the wheel mounting flange to wheel mounting flange dimension, then be sure your chosen wheel tire combination will fit under your fenders.
I doubt the Minor is 61" tread width. That is as wide as LARGE American sedans.
 
#3 · (Edited)
Tread width is the width of one tire at the tread where it runs on the roadway.
Section width is the fattest part of the tire, usually about halfway between the tread and the wheel.
Track is the width laterally from the centerline of the tread of one tire to the centerline of the tread on the other tire at either the front or rear of the vehicle.

It's interesting to note that railroads and early automobiles both used the same track width of 4 ft., 8 1/2 in. which was the exact track width used on Roman chariots.

The Morris has a front track of 50.6", while the M II is 55.6", so you would have to deal with 2 1/2" wider on each side of the car. Using a wheel with a deeper backspace could make up some of the difference, as long as you didn't get the wheel/tire into the suspension components.

Here's how one fellow split the body down the middle and added material to widen the entire car to make it work....
http://beardmorebros.co.uk/website pages/new_project_bodywork_page1.htm

And another fellow who used the above-mentioned wheel offset to get there...
http://www.carcentric.com/2Minors.htm

Don't even think about narrowing the crossmember and rack. You'll change the instant center and all associated geometry and render the whole mess into junk.
 
#4 ·
ScoTFrenzel
Total Body width is 61"

techinspector1
The Morris has a front track of 50.6", while the M II is 55.6", so you would have to deal with 2 1/2" wider on each side of the car. Using a wheel with a deeper backspace could make up some of the difference, as long as you didn't get the wheel/tire into the suspension components.

This is what I was looking for. So Mustang II IFS would be to wide.
Thanks
 
#5 ·
All depends on your fabrication skills as to whether it is too wide or not. You could fashion some fender flares to widen the body a little and use offset wheels. Where there is a will, there's a way.

You are not limited to using a M II of course. Look around at some of the Toyotas, Nissans, older Datsuns, Hyundais, Kias, Hondas, etc., etc. Most of them will probably have the strut front suspension, but if you look at trucks, you'll probably find unequal length A-arms. Take a tape measure to the boneyard and measure center to center of the front tires. I'll bet you could find a half dozen good candidates in a matter of hours.
 
#6 ·
impalaman63 said:
ScoTFrenzel
Total Body width is 61"

techinspector1
The Morris has a front track of 50.6", while the M II is 55.6", so you would have to deal with 2 1/2" wider on each side of the car. Using a wheel with a deeper backspace could make up some of the difference, as long as you didn't get the wheel/tire into the suspension components.

This is what I was looking for. So Mustang II IFS would be to wide.
Thanks
Some use shorter A arms, but that will cause tire to suspension issues.

MII front ends are commonly narrowed or widened to fit the receiver chassis.
Your only modification is the center steering link width.
The front end ackerman turning geometry would be slightly altered, which shouldn't be any real big deal. Most cars drag one wheel during tight turns anyway. Ever hear tires squeeling in the parking lots?
Your next concern is for sufficient engine room width with the 5" narrowed suspension.
The operation should be simple, but not necessarily easy.
But we are hot rodders, and that's what we do. Right? :thumbup:
 
#7 ·
techinspector1 said:
Tread width is the width of one tire at the tread where it runs on the roadway.
Section width is the fattest part of the tire, usually about halfway between the tread and the wheel.
Track is the width laterally from the centerline of the tread of one tire to the centerline of the tread on the other tire at either the front or rear of the vehicle. .....
I also refer to the centerline of tire to centerline of tire as the track but have found various plans from 1920's and 30's that refer to this dimension as the 'tread'.
 
#8 ·
scrimshaw said:
I also refer to the centerline of tire to centerline of tire as the track but have found various plans from 1920's and 30's that refer to this dimension as the 'tread'.
Many modern vehicles list the tire centerline to tire centerline as TREAD width.
For example..... ALL FORD products have always done this, and still do for 2009.

Oh and for you Chevy guys on this Chevy web site = so does Chevrolet use the term TREAD width.

Just Google it for more facts than you can stand. :welcome:
 
#9 ·
ScoTFrenzel said:
Many modern vehicles list the tire centerline to tire centerline as TREAD width.
For example..... ALL FORD products have always done this, and still do for 2009.

Oh and for you Chevy guys on this Chevy web site = so does Chevrolet use the term TREAD width.

Just Google it for more facts than you can stand. :welcome:
You know fellows, you can always find something written by someone on the internet to support your faulty argument. One glaring example is the use of "normally aspirated" in place of the proper "naturally aspirated".

If, however, you refer to the proper sources, you can usually find the proper nomenclature for whatever it is you're talking about. Here's one article from the Society of Automotive Engineers that refers to track width in it's proper use. I'm sure there are many other references in their publishings, but I am not so inclined as to spend my time looking for them.....
http://www.sae.org/technical/papers/2006-01-0795

Here's another article that sets a distinction between track width and tread width....
http://www.sae.org/technical/papers/680772

Not to say that it doesn't exist, but I would just like to see information from an OEM which lists tread width as the measurement between the centerlines of two tires on the same axle. Please provide me with a link. Anything that lists tread width as a measurement in the 50-60 inch range will do nicely. Thank you.
 
#11 ·
#12 ·
techinspector1 said:
Thank you for the reply, but one drawing done 79 years ago hardly sets the tone for an argument with the SAE of today concerning the definition of tread width and track width.
Whether or not you or I think it is correct (and I still agree with you that the proper term is track) it is obviously interchangeable as I proved and you quickly dismissed as being too old even though I would of thought age gave it credence. A quick google will reveal both uses.
Think of it as
a) the tread of a tire
b)the tread of the car

BTW from an OEM -- http://www.mazda.com.my/upload/pdf/MX-5-Specification_MY.aspx
 
#13 ·
scrimshaw said:
Whether or not you or I think it is correct (and I still agree with you that the proper term is track) it is obviously interchangeable as I proved and you quickly dismissed as being too old even though I would of thought age gave it credence. A quick google will reveal both uses.
Think of it as
a) the tread of a tire
b)the tread of the car

BTW from an OEM -- http://www.mazda.com.my/upload/pdf/MX-5-Specification_MY.aspx
Sorry, I didn't mean for it to seem that I was "quickly dismissing" your entry. It's just that things change and while the correct nomenclature of the day when the drawing was done may not be the accepted or correct nomenclature of today.

You entry from Mazda is most interesting though and you have proved your point. Thank you.
 
#16 ·
Here's a definitive answer

Ahem. Being an automotive engineer with some credence elsewhere, you can trust me on this one:

There is some confusion in the industry between track width and tread width terminology. SAE refers to it one way, the government the other.

SAE Track width is the distance between the geometric wheel centerlines as measured at the axle height. Some manufacturers (Ford Included) report this in their advertising as the track width.

SAE Tread width is the distance between the tire centerlines at the tire contact patches as measured at the ground. The government refers to this as the track width.

The difference between these measurements is caused by camber angle. If the vehicle has a negative camber angle, the SAE Tread Width is going to be larger than the SAE Track width.

Hopes this helps.
 
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