Experiment Request: Traction at 50 psi vs 30 psi

[brucepick]

No takers yet who might run the test?

[psyshack]

I willing to do the test. Just thinking about where I could do it. Would want to do it in both the Accord and Mazda3. The Accord with its LLR Micky's and the Mazda with its Goodyear RS-A's.

Let me ponder this a bit.

[DarbyWalters]

As long as temps (tire and surface) are equal starting out...the lower inflated tire will out brake the higher inflated tire (as long as they are both within the acceptable range).

Be careful not to "flat spot" a tire and ruin it~

[skewbe]

The comments on this site suggest that there is an optimum psi for performance, not too much and not too little. I'd rather have the extra mpg myself on the street. 'Course if everyone on the world maintained 36 psi we would save a lot of gas, not enough though.

http://grassrootsmotorsports.com/new...-vs-falken.php

Comments:
Set 1 baseline at 36 psi. Tires were at ambient temp to start.
Set 2 add 4 psi to existing pressure and performance drops by 1-2 tenths.
Set 3 drop 4 psi back out to bracket the test and performance is restored.
Set 4 drop another 3 psi and performance drops slightly. Tire gets squirmy.
Set 5 drop another 4 psi and performance drops even more.
Set 6 back to previous best to bracket the test and performance is restored.

[JanGeo]

Roads around here are covered with ice and snow and it is raining - just shoveled the driveway for half an hour to make 2 tire tracks and moved my xB away from a tree limb in preparation for the wind storm due later tonight.

[VetteOwner]

Originally Posted by Erdrick

M+S most certainly is the designation for snow tires. It stands for Mud and Snow. They aren't rated the same as regular (all season and most other types of tires) tires, and are missing things like tread life ratings.

While I haven't done an actual ABA test on this, I can say that my braking distances did increase after pumping up my tires. It would be interesting to see someone's results after doing this test, but there really is no reason to debate the issue. Harder tires roll better, and more rolling resistance is what you want to help you stop your car. Thus, tires with low rolling resistance that are pumped up to a high pressure will take a longer distance to stop than higher rolling resistance tires that aren't pumped up that high.

I do want to see some actual data on this though...

no theres a difference bewteen M+S and just snow tires. snow tires are made out of a soft rubber and usually pretty block like tread. they wear down VERY fast on dry pavement, but offer excelent grip on snow.

M+S aka all season are well all season tires, meaning they generally last alot longer than snow tires but not the longest lastign tires out there. thier not excelent at any one surface but a good grip on a variety of surfaces(dry, wet, snow, loose (liek mud/ gravel roads etc)

i can take a picture later of different treads(snow vs m+s) and u can visually see the difference

[kamesama980]

All M+S means is that the grooves go from one side to the other and there's a lot of groove area. snow tires can be M+S or not, all seasons can be M+S or not. every tire I've owned has had the M+S designation along with all the DOT required ratings. M+S means little. the tires I'm using now are M+S rated but suck in the snow.

Again not ABA testing but when I've been to drifting and other autosport events (dry events), you never see tires under 45 psi unless someone forgot to check them. I tried at 30-35psi once and it sucked (and chewed the crap out of the tires) up the PSI to 50 and it's much easier to both break them free (less traction in back) and control the vehicle (less flex in front).

When there's some clear pavement I'll do some testing.

[brucepick]

Good to see a couple folks interested in testing this.
Thanks, psyshack and kamesama980.

[psyshack]

I want to do a 30 mph and 60 mph test groups.

Do the test with the tires warmed up. Meaning scrub them in for the first test then keep them warm with in reason thru out.

PSI on Mazda would be something like 34, 55, 34
PSI on Honda would be something like 34, 44, 34

Use chalk for a brake point marker, and stopping point for each car. So forth and so on.

Just need to find a safe place to do the test. Going to talk with the local airport auth. and see if I can do the testing out there. Small local airport. See if the good old boy network comes thru......

[Mayhim]

If you're looking for quantification, carry on. If you're looking to find out if it's a fact, it is.

All you have to do is see how much wheelspin you can get at a high rpm clutch dump with 30 psi then at 50 psi.

High psi = no tire/tread deformation and conformation to the road = no grip = lots of wheelspin. Ask anyone who has a hotrod.