I have read similar questions, but this is a little more specific.
How does tyre pressure affect tyre wear on mud type tyre when traveling on sealed roads? I understand the reason behind scallops on the lugs due to the scuffing as the tyre rotates. I have only had AT type tyres and had good wear generally running lower than average tyre pressure. So in a mud type tyre would lower pressure lead to more scuffing or is it better to run slightly more than average pressure to reduce the effects of scalloping on the lugs.
This question applies only to sealed road driving and wear, regardless of the 4PSI rule, tyre placard or max pressure on tyre.
I eagerly await your knowledgeable replies based on experience or whatever.
Craig
safari wagon
18-07-2007, 01:07 PM
i generally run slightly higher pressures, 38 psi. it makes it a little rougher but the shoulder of the tyre doesn't wear as quick. you can notice how much the tyre flexes when you use lower tyre pressures then go from dirt to bitumen. the parts that scuff go normal black and the rest stays dirty. i was surprised on how far down the side wall lugs get scuffed. almost to the side wall.
Peter @ Aawen4x4
18-07-2007, 03:14 PM
I would have thought that by using the 4psi rule you'd find that the better pressure is actually a little lower than what most consider 'normal'; ie, I run my 33 STT's at about 26-28 psi while most others seem to run them at 30 plus pressures, and I get WAAAAYY less scolloping and other wear. And I notice that it is a fairly small range of 'correct pressure' too. Pressures just a little over the 4psi get wear in the centre of the tread and more scolloping along the lugs; while pressures running just a little too low get no wear in the centre of the tread and wear only on the outer edges of the lugs.
My take on it is that at the 4psi pressure, the sidewall does the flexing, enough to leave the tread blocks & lugs seated firmly in place, instead of higher pressures forcing the lugs to squirm instead of sidewalls, beginning to lift off on one the leading edge while the trailing edge is still grounded but squirming cos the sidewall isn't! And it's noticeable, higher pressures, more heel toe effect spreads across the face of the tread and further into the middle of the tread, lower pressures the heel toe effects only the outer edges of the tread, the lower the pressure the closer to the edge is the spread. Another thing to do is to rotate the tyres religously!! I rotate mine front to rear, to spares, to opposite front, every 10,000km, along with the 10,000 km wheel alignment and balance.
Any indicators to suggest you should rotate them NOW??!! Sure are! Just run your bare hand over the tread face in the forwards and the reverse direction. If you've done any km's you'll notice that the leading edge of the lugs feels sharper than the trailing edge of the lugs. And in noticing this, you should also be able to tell that the tread blocks in the centre of the tread don't exhibit this anywhere near as much! It's the rounded and less sharp edge that is experiencing the greater wear! If you run pressures in the higher end of the scale, I find that the sharp edge increases and the rounded edge is more pronounced, while lower pressures leaves less pronounced sharp edges and as you get lower, the rounded worn edge to the lugs effects more of the perimeter of each lug! So it highlights the optimum pressure, and just happens to be the 4psi increase after 1 hours driving!! BUT, you do hafta do that measurement and calculation across the range of parameters that will vary for you, and you need to do the check after an hours driving every time you drive, just to get the pressure set correctly! Still, since it means that I get better life out of the tyres, and better traction, wear, road holding, etc, surely it's worth it!!
BTW, the heel/toe sharp/rounded edge thing effects larger (wider) blocks more than smaller (narrower) blocks! And the speed that you drive at will cause far greater wear the faster you go!
Enjoy!