Tyre Pressures-Chalk Test

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The Mad Hat Man

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LZIR Despatch Agent
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do the chalk test.

blow them up to a nominal value,
rub a line of chalk across the tyre,
drive a couple of hundred yards in the dry,
look at chalk mark,
if centre of chalk mark is worn off, decrease pressure,
if outside of chalk mark is worn off, increase pressure,
repeat until all of chalk is worn off uniformly,

tyre pressure is ideal for your motor, loaded as per test.
 
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Also depends on what use you are using the vehicle for. Towing you'll probably want slightly over inflated, off road under inflated. And tyre type, side wall height, ply thickness. Suspension geometry will also affect this, as the chalk test assume the tires is completely vertical with 0 toe in/out, no caster and 0 camber.
 
Sounds like someone is trying to re-invent the wheel (no pun intended)
Over the last five decades I have realised decent mileage averages on tyres just by sticking to the manuf. stated settings, without faffing about with bits of chalk.
 
blow them up to a nominal value,
rub a line of chalk across the tyre,
drive a couple of hundred yards in the dry,
look at chalk mark,
if centre of chalk mark is worn off, decrease pressure,
if outside of chalk mark is worn off, increase pressure,
repeat until all of chalk is worn off uniformly,

tyre pressure is ideal for you motor, loaded as per test.
Sheesh!....this is about one of the best ways of spotting a deflated or over inflated tyre! This I must try as looking at other threads tyre pressures thet range from 24 to 32 bar!!!! Thanks tmhm!
 
Ok Pals.
Getting some dry weather would be a start. Until then I'll stick at 32 lbs and see how we go.
Must say though, can really feel the difference with these tyres on compared to my old set. Now, they were road tyres and yet the new set has better road grip.
I'll see how they fare off road in a week or so.My hobby takes me off road (shale, small rocks & mud) every other weekend, so well see how we go.
Cheers ALL.
 
Sheesh!....this is about one of the best ways of spotting a deflated or over inflated tyre! This I must try as looking at other threads tyre pressures thet range from 24 to 32 bar!!!! Thanks tmhm![/QUOTE

I hope that's ment to be psi because 32 bar is a bit high. :eek:
 
I usually just go with the manufacturer's recommendation. I'm too lazy to play around with chalk. Did you make a hop-scotch on your tyres?
 
I usually just go with the manufacturer's recommendation. I'm too lazy to play around with chalk. Did you make a hop-scotch on your tyres?

Recommendation doesn't take into account actual loading. Which may vary widely.
We used a version of the chalk test to inflate tractor tyres, although we didn't actually use chalk. We just parked the tractor on a concrete floor, and then inflated until the lugs were flat on the floor across the bottom.
The actual pressures would be quite different if you had an implement or lift box on the arms, or unladen.
 
I once got a company 4x4 back from the garage with 80psi in the tyres. “That’s what’s written on the sidewall.” Said the ‘mechanic’. It made the vehicle a bit bouncy and directionally unstable.
Mind you, this was in Australia, perhaps they do things differently there.
 
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