2nd Gen Non-Engine/Transmission Tire pressures for O/S tires?

[CnH2n+2]

Just curious what the recommended pressures would be for an oversized tire? Specifically a 315/75/16. With the stock 245/75/16 tires I kept them properly inflated at 65psi in the front and 80psi in the rear according to the factory specification placard. Should I run the same pressures for the new tires or is a different pressure recommended?



Thanks.

 

[AKAMAC]

Depends on the load rating of the tire. If you're running "d" rated I'd run at or close to recomended pressure on side of tire. Mike

 

[CnH2n+2]

Well the stock size tires I had were Load E rating. The Max Press on the side of the tire was 80psi. I ran the rear at that, but Dodge recommended the front to 65psi so I ran that and changed them upon rotating. Just wondering what others are running, if they are running the same all around, or staggard like the factory settings.

 

[AMink]

On my 285/75-16s, I'm running about 45 front, 35 rear unloaded. They are D rated and when I load up or tow, I bump them up. I was running closer to the max (65), but the middle of the tires were wearing more quickly than the edges. After driving on wet pavement, the outer 3/4" or so of the tread wasn't even on the ground! So I aired down until the whole tread was flat on the ground. Rides better and no other issues so far. The stock 245's at 80 in the rear were brutal when empty. I don't know if there is any "table" that is a little more scientific than my way, at least I haven't seen it.

 

[NIsaacs]

As a general rule, the larger the tire, the less air is needed for the same weight capacity. The weight chart on your door is for max GVW. Running empty, the front will require more air than the rear also the faster you drive, the more air you will need. I run 45-50 front and 35-40 rear with my 285's. When I tow or haul a load, I air up the rear accordingly.





"NICK"

 

[FDziurda]

Tire Pressures

I use the following method and it has always worked great for me.



Take you truck to a scales and have it weighed. You need to know the front and rear axle weights.



After you know the axle weights, look at the side of your tires to see what the ratings are. It should say something like 3042 lbs at 80 psi.



To determine the proper tire pressure, divide the axle weight by the load capacity of the tires and then multiply it by the max tire pressure. For example, my truck's rear axle weighs 3300 lbs and the tires are rated at 3042 lbs each at 80 psi. 3300/6084 x 80 psi = 43 psi. I run my rears at 45 psi, to make it easier to remember. This procedure should work regardless of the tire brand you are using. In addition to knowing the tire pressures, you will also know what load your rear axle is capable of hauling. If your rear axle weighs 3300# and the tires are rated for 6084#, you safe load capacity is 2784#.



Good Luck,



Frank

 

[CnH2n+2]

Thanks everyone for the suggestions. I have a good basis to start from.

 

[CnH2n+2]

One other question. Can the pre-96 trucks' speedo be recalibrated at the dealer? I know the dealer can do the 96 and up trucks for sure. If you have larger then 265's you can just imput the revs per mile, but I wasn't sure if mine could be done there or not.



If not, what is everyone else using?



Thanks again.