Tires and MPG

[03z71]

I know this topic has been beaten to death, but fuel economy has not been the main focus in the LT vs. P rated tire debates. I am about ready to replace my OEM P rated tires on my 2003 Silverado ECSB Z71. I don't tow or haul anything except for a 600 lb (loaded weight) boat trailer (VERY small boat!), so P rated tires would be suitable enough for this truck - I don't want to debate load handling characteristics. That being said, I prefer the ride of LT rated tires and like the idea of sturdier construction (even though I don't "need" it). My concern is fuel economy. When I replaced the OEM Goodyear P-metric tires on an a GMC Jimmy I used to have with LT (load range C) Revos, my MPG dropped by a solid 10-15%. I'm not sure if it was the tread design, rolling resistance, weight, or a combination. I don't want a repeat of that again. I would have thought that since I inflated the LT tires more (45 vs 35 psi), they would actually help fuel economy or have no effect. Can anybody quantify the difference in fuel economy between LT rated and P rated tires of the same tread pattern? I am planning on buying Cooper Discoverer ATRs, but just can't decide between P and LT. If I thought MPG would be the same, I'd go LT in a second. I just don't want to pay more for the tires and continue to pay more in gas for the next 50-60,000 miles when I don't "need" LT tires...

[MS3DALE]

I've never noticed any loss in MPG going from "P" to "LT" tires,but I still run 35 psi in them.

I've never run 45psi,Thats a little too high for me and what I need.

Try running the "LT" tires with 35psi in them and you should be OK.

[MustGoFaster]

looked at my tires over lunch - they're rated at 50 psi! I checked and theyre filled to 35. I might run them at 50 and see of I notice a change in MPG

[jhm]

I got Cooper AT's as replacements for the oe P metric goodyears. The only downside I noticed right away was the P metrics gave the truck a ride quality similar to a Caddy. The LT's definately gave a harder ride, it is really quite noticeable. I never checked gas mileage with the oe tires so I don't know if it went down or not.

[03z71]

I've never noticed any loss in MPG going from "P" to "LT" tires,but I still run 35 psi in them.

I've never run 45psi,Thats a little too high for me and what I need.

Try running the "LT" tires with 35psi in them and you should be OK.

 

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Well, that's good news for the LTs. When I ran the LTs at around 35 psi, they were even worse than at 45 (as would be expected).

[pm26]

looked at my tires over lunch - they're rated at 50 psi!  I checked and theyre filled to 35. I might run them at 50 and see of I notice a change in MPG

 

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Just because the tires can handle 50 psi, it does not mean that this is the recommended inflation pressure for your truck. Follow the manufacturer's recommendation.

[SoCalChris]

I just switched over from P to LT tires. I'm pretty meticulous about keeping track of the mileage, so after I've gone through a full tank (Probably another week or two), I'll post the before & after.

[firstruck]

LT tires tend to weigh more than P's. An equivilent LT tire is roughly 10 or 11 lbs heavier than a P and are constructed differently generllly leading to decreased mpg's. I'll be interested to see your follow up Socal as I'm currently looking to put LT's on my wifes rover... is it possible to get negetive mileage?.......

[03z71]

I just switched over from P to LT tires. I'm pretty meticulous about keeping track of the mileage, so after I've gone through a full tank (Probably another week or two), I'll post the before & after.

 

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I will also be anxiously awaiting your results.

 

At this point, I am leaning towards P-metric tires for the up front cost and more importantly potential MPG savings. My dealer actually recommended P-metric for my use. I'd rather have the LTs for ride, but I am just too scared of killing my mileage. I didn't buy a full size truck expecting to get 35 MPG - but at the same time, I don't want to decrease my mileage just because of a tire choice...

[Shaners]

Another thing to remember is that if your new tire is the same size as the old one, but has a more aggressive tread, then you will see a decrease in your milage in most cases.

[03z71]

Another thing to remember is that if your new tire is the same size as the old one, but has a more aggressive tread, then you will see a decrease in your milage in most cases.

 

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True. I'm hoping that tread won't have a big impact either. The tread pattern won't be a huge difference in my case (except for the depth of new treads vs. treads with 65,000 miles on them).

[redvett]

If your not going to tow or haul anything heavy stick with the OEM tires. They are selected by GM for best ride,mileage & all around driving. I replace my service truck with OEM tires and never have a problem. My employes do a lot of driving and never have a problem.

[SoCalChris]

If you do a lot of driving on unpaved roads, stay away from the P rated tires. The OEMs that came on my truck were getting ripped apart by my 40 miles of daily unpaved road driving, after just 5,000 miles (Hence my switch to LT rated tires )

[firstruck]

If your not going to tow or haul anything heavy stick with the OEM tires. They are selected by GM for best ride,mileage & all around driving. I replace my service truck with OEM tires and never have a problem. My employes do a lot of driving and never have a problem.

 

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What are you smok'in? OEM tires are junk. They're selected by GM becauase they're cheap and an ultimate comprimise between all those things.

[redvett]

I am not smoking and if you go to the tire dealer or tire store and buy the same tire that was on your truck it will perform just as good as the OEM and save you money in gas and ride. I currently have 3 service trucks all the same 2001-02-03 & my personal truck that are 4x4 EXT cab short box and my employies drive them everyday in northern MI on service jobs and i have never had any problems. Loaded these trucks average 16 mpg. I have kept records on my trucks for years and can account for every penny spent. The OEM tires have never failed my people and provide good fuel economy and realibility.