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Topic: Close weight measurement (Read 1047 times) previous topic - next topic

Close weight measurement

We were discussing this the other day at work. (I am in research and development for Bridgestone Firestone). To get an approximate total weight and weight distribution for you car you need to do a couple of measurements.

1. Slide a piece of construction paper in front of the tire until it stops, then place another one behind the tire until it stops. Measure the distance between the two pieces of paper.

2. Slide a piece of paper on each side of the tire until it stops, measure the distance between the two pieces of paper.

3.  Multiply the length of the tire times the with of the tire and get the "footprint" of the tire in square inches.

4. Take the air pressure of the tire.

5. Repeat for each tire.

6. Multiply the "footprint" times the air pressure and you get the approximate weight that the tire is supporting.

I haven't been able to try this with my car yet, because it is still in winter storage. It would be interesting if anyone has had their car weighed and tried this to see how accurate it really is.

Close weight measurement

Reply #1 –
Cool, I'm gonna try it!
[SIGPIC][/SIGPIC]
86 5.0 Turbocoupe (Katrina), 87 5.0 Sport (Rita)

Close weight measurement

Reply #2 –
I don't see how that could possibly work.

A simple tire size change would change it

Air pressure of 10 in one tire as oppose to 60 in another would alter those numbers, but not change the weight distribution of the car at all.
I could be wrong, but I don’t see it (then again maybe thats why I'm not R&D for Bridgstone Firestone)
:birdsmily:   Objects In Mirror Appear to be Loosing  :birdsmily:

Close weight measurement

Reply #3 –
The "footprint" of the tire depends on the amount of air pressure in it. The more pressure, the smaller the footprint, the less pressure the larger the footprint.

Ex. If the footprint of the tire is 5" x 4" (20sq in.) and the pressure is 30psi. Theoretically, that tire is supporting 600 lbs.

Say that same tire now only has 15psi in it, then the footprint would enlarge to say 6.75" x 6" (40.5sq. in) then theoretically that tire is supporting 607.5 lbs.

Its not meant to be an exact measurement, just a rough ball park.
The more weight that is placed on a tire will cause it to "mushroom". Thats why when you place a heavy load in the back of a pickup the tires always look like they are low on air.