Chalk Test & MPG Update - 275/70/18 Toyo Open Country AT3 E Load

[Joestac]

Started them at 35 and tried 38 as well before chalk. 38 was a bit too sensitive on small bumps so I snagged some chalk and dropped them back to 33 front and rear.

Looks pretty even to me. Going to see how it rides this week then go from there. Highest I'd probably go would be back up to 35 cold.

Still liking these tires more than both the KO3's and the AT4W's.

MPG log also attached.

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[BonRunner]

I got the same tire size on AT4W. Got them for an amazing deal, although they're a bit rough, I've learned to love the AT4W. How do u do the chalk test?

 

[Joestac]

How do u do the chalk test?

I live in a cul-de-sac. Drove to the end of my driveway and chalked the front and rear driver side tire. Drove to the other end and checked the wear pattern of the chalk on the tire.

If the edges have more *wear than the center there is too little air. If the center has more *wear than the edges there is too much.

I kind of wanted 33 anyway, so I didn't see how low I could go.

Edit: Corrected for wear.

 

[SNDR]

This is known as the pollen test in New England around this time of year

 

[HLL]

"Hmm, I thought E-rated tires were supposed to run at 40–45 psi. Doesn't running them at 33 psi increase the risk of a blowout?

 

[Joestac]

"Hmm, I thought E-rated tires were supposed to run at 40–45 psi. Doesn't running them at 33 psi increase the risk of a blowout?

That is kind of the point to a chalk test. This ensures the right contact patch to the ground while also offering a less stiff ride.

If I were under load I'd go up in PSI. When warm they are running closer to 36.

 

[RunnerRocks]

"Hmm, I thought E-rated tires were supposed to run at 40–45 psi. Doesn't running them at 33 psi increase the risk of a blowout?

https://www.toyotires.com/tires-101/tire-load-and-inflation-tables/

 

[ShotsFired]

Chalk test, very interesting. When I bought my 4Runner the tire pressure was at max 50 PSI. The ride was a little rough that's why I checked. I lowered them all to 40 with very little improvement in ride quality. Dunlap tires. May try this test. Thanks for your post.

 

[Joestac]

Chalk test, very interesting. When I bought my 4Runner the tire pressure was at max 50 PSI. The ride was a little rough that's why I checked. I lowered them all to 40 with very little improvement in ride quality. Dunlap tires. May try this test. Thanks for your post.

Yeah, they usually over-inflate tires as a common practice when transporting. Always a good idea to check pressure on new vehicles for sure.

 

[Joestac]

https://www.toyotires.com/tires-101/tire-load-and-inflation-tables/

If I did the math right, this table does indicate running them at 45 PSI is recommended at max load. Still seems high seeing how stiff they were at 38. I wonder what a chalk test at 45 would look like.

 

[bakutheleo]

"If the edges have more chalk than the center there is too little air. If the center has more chalk than the edges there is too much."

@Joestac I believe you wrote that backwards...I think you meant "If the edges have more *wear* than..." and "...center has more wear...."

 

[Joestac]

"If the edges have more chalk than the center there is too little air. If the center has more chalk than the edges there is too much."

@Joestac I believe you wrote that backwards...I think you meant "If the edges have more *wear* than..." and "...center has more wear...."

Accurate. Thanks for clarifying that.

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