C Load or P Load?

[1engineer]

Here are the weights of the A/T3 for 17" wheels as provided to me directly from Cooper last week in case anyone is interested:

The Lt275/70R17 (E), (C), and Lt285/70R17 (E) Cooper Discoverer A/T3 tires should weigh the following listed weights:

LT275/70R17 E A/T3 spec 5875 weighs 51.88 pounds

LT285/70R17 E A/T3 spec 5850 weighs 55.17 pounds

LT275/70R17 C A/T3 spec 5871 weighs 50.70 pounds

Interesting that the E only adds a pound over the C in the 275. FYI, I also checked the bad ass S/T Maxx in a 285 E, and was told it weighs a whopping 60 pounds. With its sidewall reinforcement I would have a lot more confidence in it over the 285 DuraTrac off road, but it is 7lbs. heavier.

My stock size P rated Cooper AT3 tires are 41 lbs.

 

[453030]

My stock size P rated Cooper AT3 tires are 41 lbs.

Thanks 1E. That seems like a terrific replacement to the stock tires.

 

[DannyLlama]

Still waiting to hear back from cooper on the official answer.

I just hope the 275's don't have fitting issues. It seems to be ok with others on here. *crossing fingers

 

[ColoradoFrosty]

No problems with the fit at all... you are gonna love 'em! :trophy:

 

[JB.]

Not sure how I can say it differently, but the carcass on the P tire is larger with respect to the overall diameter than the similarly sized LT tire. Obviously enough to make a difference. That, or you are right, the info is not accurate.

Go to Discount Tire Zone on the web.

Sure enough, it says 52lbs, but I've never seen a P-metric tire (in this case metric, the european equivalent) that weighed that much compared to the LT versions and I remember from my own tire buying process how inconsistent internet tire specs were. Even some of the emails from tire companies were less than confidence inspiring.

The max load/inflation info looks odd to me, too, even allowing for it being metric sizing or trying to make it work out for an Extra Load tire. Who knows, but with 1Engineer now reporting his tire weight, I'm still thinking publishing error.

 

[DannyLlama]

No problems with the fit at all... you are gonna love 'em! :trophy:

Mine are 18's. 275 65 18

 

[OrangeTexan]

Sure enough, it says 52lbs, but I've never seen a P-metric tire (in this case metric, the european equivalent) that weighed that much compared to the LT versions and I remember from my own tire buying process how inconsistent internet tire specs were. Even some of the emails from tire companies were less than confidence inspiring.

The max load/inflation info looks odd to me, too, even allowing for it being metric sizing or trying to make it work out for an Extra Load tire. Who knows, but with 1Engineer now reporting his tire weight, I'm still thinking publishing error.

Your probably right about it being a publishing error. I went back and checked the weights they list for the tire sizes "453030" listed from his correspondence from Cooper, and some of the weights listed on Discount Tire Zone dont match his numbers. However this is the only resource I have found (and it wasnt exhaustive searching, to be honest) on the web for Cooper weights. Seems if we want some real numbers we can trust we need to ask Cooper directly, and keep looking for a better web source.

 

[DannyLlama]

Lugnuts

Does anyone have a recommendation where to buy lock Lugnuts? Need it in black

 

[453030]

Your probably right about it being a publishing error. I went back and checked the weights they list for the tire sizes "453030" listed from his correspondence from Cooper, and some of the weights listed on Discount Tire Zone dont match his numbers. However this is the only resource I have found (and it wasnt exhaustive searching, to be honest) on the web for Cooper weights. Seems if we want some real numbers we can trust we need to ask Cooper directly, and keep looking for a better web source.

I originally asked my local Discount Tire and the weights they had were maybe 2 or 3 pounds heavier. When I emailed Cooper, they originally replied with the exact numbers Discount gave me. Then a day later they informed me my inquiry lead them to discover a discrepancy and they attached the new lower weights I posted in this thread. Who knows, I hope the latest numbers are accurate!

 

[ColoradoFrosty]

Mine are 18's. 275 65 18

Oh that's right...

Metric to Standard Result:

• 275/70/17 = 32.2x10.8/17

• 275/65/18 = 32.1x10.8/18

 

[DannyLlama]

411

I e-mailed so much back and forth with Cooper that I was finally provided with a number to call and the rep was actually quite helpful and extremely informative.

Here's the break down -

P - 275/65/18 42 LBS 4 Ply - Load is 114 (2601LBS) Speed rating T
P - 265/65/18 43 LBS 4 Ply - Load is 114 (2601LBS) Speed rating T

C - 275/65/18 51 LBS 6 Ply - Load is 117 (2756BS) Speed rating S

She was also trying to convince me NOT to buy these tires as the Limited speed rating is - H and the T is 2 step below. She advised me against that and suggested that I stick with manufacturer specs. I'm sure this was said to protect her self from a law suite.

It did get me worried again. Am I putting my family in danger by manpulating the standard speed rating? Than again, we aren't racing at a 120 MPH.


In addition (1engineer) is going to cringe at this . I tried to do some MPG calculations and I'm thinking I will loose about 1-2 MPG with this change. The over all weight is the same, except the diameter is a little bigger and more friction.

I really don't know what to do, keep the purchase and get them installed or just forget about off roading over and never mind the purchase. No one has to answer , just thinking out loud :gun4:

 

[JB.]

I'm about as conservative with inflation pressure and tire construction as any layman you're likely to run into and I don't think you should be concerned especially since you're going with the P type tire.

The first thing I'd say is ask the tire engineer.

Since no one seems to like that option, I'll point out that, yes, you've decreased speed rating but you've also increased load capacity (LE comes stock with 245/60/20, right?), the two being somewhat related.

The speed rating thing was more important before many lower speed rated tires started being constructed with nylon cap plies as H and higher speed rated tires have always been. I've looked before and concluded that the Cooper AT3 is so constructed. Most recently designed tires are.

 

[1engineer]

I'm about as conservative with inflation pressure and tire construction as any layman you're likely to run into and I don't think you should be concerned especially since you're going with the P type tire.

The first thing I'd say is ask the tire engineer.

Since no one seems to like that option, I'll point out that, yes, you've decreased speed rating but you've also increased load capacity (LE comes stock with 245/60/20, right?), the two being somewhat related.

The speed rating thing was more important before many lower speed rated tires started being constructed with nylon cap plies as H and higher speed rated tires have always been. I've looked before and concluded that the Cooper AT3 is so constructed. Most recently designed tires are.

I do not design tires for a living and the fellow JB is referencing is very good. You are to the point of asking him and additional questions. Good luck.