Interesting Test for all you DarkSiders

[Igofar]

This method of checking tire pressure, called the chalk test, demonstrates if your tire is bulging from too much pressure or if it is slightly concave from a lack of pressure

Instructions

1. Fill the tires to a good starting pressure. If you are unsure what pressure to start with then subtract 10 percent from the manufacturer's maximum inflation pressure on the side of the tire. If, for example, the maximum is 40 psi, then 10 percent of 40 is 4. Subtract the 10 percent value from the maximum psi value. So, 40 - 4 = 36. Use 36 psi in your tires. You could also use the following calculation for the starting pressure.
   • Weight of vehicle / (Manufacturers weight rating x 4)) x Manufacturers inflation pressure at weight rating
2. Drive to a flat area. This can be your driveway or the street in front of your house. Just make sure there aren't a lot of cracks, bumps or pot holes in the ground.
3. Using chalk, draw a thick, straight line across the width of the tire.
4. Use Test Variance 1 or Test Variance 2 for the completion of the instructions.

Test Variance 1

1. Drive the truck forward at least one-full truck length.
2. Inspect the chalk on the ground. A tire with the proper air pressure should press the chalk line evenly across the ground. This means you'll see the entire chalk line imprinted on the ground. If your tire is over-inflated, you'll only see a small portion of line in the center. If you're tire is underinflated, you'll see only the sides of the lines since the middle of the tire is not making contact with the ground.
3. Adjust your tire's air pressure according to the chalk test results and try again until you get the chalk line to press evenly across the ground.

Test Variance 2

1. Drive the truck to the end of the street and back or around the block.
2. Inspect the chalk on the tire. A tire with the proper air pressure will show the chalk evenly worn across the tire. If your tire is over-inflated, the center of the line will be worn more than the edges. If you're tire is underinflated, the outer edges of the line will be worn more than the center.
3. Adjust your tire's air pressure according to the chalk test results and try again until you get the chalk line to evenly wear across the tire.

Over-Inflated = More wear on the center of the tire = center of chalk line visible on ground = chalk line worn more in center

Under-Inflated = More wear on the outer edges of the tire = outer edges of chalk line visible on ground = chalk line worn more on outer edges

 

[Larry Fine]

What truck?

 

[TerryS]

What truck?

Maybe that's how a bike feels with the darkside mode engaged?

 

[flyfisher]

So how do you darkside a truck?

 

[motornut]

I always watched the tire wear. which is reacting rather than anticipating. Did not cross my mind to check it this way. Which makes perfect sense on automotive usage. Seems like for darksiders the lean angle will come up with nobody knows what.
I think Darksiding a truck would mean putting motorcycle tires on the truck????

 

[Ron]

Wouldn't you want to go ride a while and get the tire and air in tire up to their operating temperature?

 

[Igofar]

I used to do this test to wing riders when they switched over to car tires.
I never had one that didn’t either show two narrow lines on the outside edges, or one very narrow line down the middle, seems it’s very difficult to find the right pressure for a car tire on a motorcycle.
And of course, all the riders swore their pressure was perfect because it’s what was recommended on the dark side face book page.

 

[Igofar]

Wouldn't you want to go ride a while and get the tire and air in tire up to their operating temperature?

Good question, a better question would be what would it take to heat up a car tire to correct operating temps on a bike?

 

[jodog]

Good question, a better question would be what would it take to heat up a car tire to correct operating temps on a bike?

In my experience the tire heats up about 10% on a normal day. It heats up pretty quickly, probably no more than 15 miles. Of course if you're riding in West Texas in August, YTMV.

 

[Ron]

Good question, a better question would be what would it take to heat up a car tire to correct operating temps on a bike?

I'm sure there are many variables contributing to tire heat.

From an article in cycle world (2010) mainly track tires..

Many tire brands give suggested cold tire pressures, Pirelli prefers to set tire pressures after the tire is up to temperature (165 degrees F on a warmer or after 10 minutes of lapping the track). Pirelli likes to see between a 3-5 psi rise in pressure from the initial cold tire to one at 165 degrees or above.

I do know if you want to heat up a tire and wheel, ride it about 15 miles at 25mph with 0 PSI in it. The wheel was too hot to hold my hand on it. Shortly there after, I bought a sticky worm kit and a mini-compressor.

 

[DannoXYZ]

Pressure-rise is common test for optimum pressure. However, it will vary depending upon relative humidity of air at time it was pumped into tyre. Also varies based upon ambient air-temp since road-surfaces may be same as air on cold days, and up to 30-40F higher on sunny days.

Difficult part of chaulk test for bikes is keeping it perfectly vertical. Since bike leans, more realistic test should be measuring for temperature across tread. Then it would show that optimum pressure would vary based upon course. A long highway ride would probably need couple more PSI than mountain twisties. Combining temp-rise along with temp-range across tread might good metric.

Wear-pattern may also reveal optimum pressure. However, again that only applies to upright straight-line riding. Regardless of pressures I use, my darkside tyres always wears out edges well before centres. Similar to my track tyres.

 

[Valker]

My Valkyrie Darkside tires are run at 26 PSI. If I'm heavily loaded-28. I run 205/65-16 Michelin CrossClimate2.

 

[Nashcat]

Great idea, Larry. I did the same type of test by driving through some water, and then across a dry driveway. The water seems to indicate the same as the chalk, plus I don’t always have any chalk.

John

 

[Obo]

Easier to darkside your motorcycle than to lightside your car....

 

[motornut]

Hey, lets talk about oil now

 

[DannoXYZ]

Hey, lets talk about oil now

Do you prefer basalmic vinagrette or….?