I recently bought a set of BF Goodrich T/A ko's. My old tires were the stock Goodyear Wrangler RT/S. I got the same size tire, P265/70R17. I have a Northstar pop-up camper on the back of a 2002 F-150 Supercab with the big V-8 and the FX-4 4x4 package. I have a K&N intake system and a Flowmaster exhaust.

I have now taken 3 trips with the new tires and my gas mileage has dropped from about 12.5 average prior to the new tires to 9.5 average. The only difference on the truck is the tires. I don't drive more aggressively than I did with the old rubber. It has me completely stumped. The air pressure in the tires is not low. %0 lb in the back and 40-45 in the front.

Anyone else experience anything like this? Any ideas?

Thanks.

Harley

 

your PSI is a little high, but that shouldnt bring your gas mileage down that low.

35-40 PSI seems to be the sweet spot for the BFGs, I wouldnt go any higher than 45.

Does it feel like you have to give the truck more gas than usual to get it moving or keep up to speed?

 

The truck runs just fine. No issues with acceleration. I put the extra air in the tires at the instruction of the tire shop, I assume due to the extra weight of the camper (approx. 1,600 lb.s).

Harley

 

That is odd...I didnt get any mileage drop (very little if any) when I changed to BFGs.

 

Harley - where do you live? In California, they are phasing out MTBE fuel and replacing it with up to 15% ethanol blends. Perhaps your gas has been changed to lower energy content without you knowing it.

IMO, Ford specifies the stock tires for their low rolling resistance to improve fuel economy. I am not surpised that heavier, sticker tires might cost some mpg, but your loss in mpg is much greater than I would expect from tires alone.

 

I seriously doubt that. But as I said in my post, regardless of if Ford does actually choose specific tires based on that (I imagine it's whatever they can get a good deal on), he shouldn't notice any great MPG loss if he stays with the same size tire.

 

Dave,

Good call, I do live in CA. I got the tires right before Christmas and went to Big Sur over Xmas. I was really bummed when I saw the kind of mileage I was getting. I have been on two trips since, with the same result. With the high gas prices in CA, that drop in mileage adds up to some serious dough very quickly.

Harley

 

Its more than likely the methanol they are adding to the fuel. The tires should not effect fuel comsumption....

 

Fuel mileage always goes down in the winter - it has to do w/ power derived from winter fuel blends vs. summer fuel blends, and fuel is less volatile when it's cold out and doesn't burn as complete. If you What part of CA do you live in? It could be any or all of these factors plus the methanol fuel factored in, too.

In the last couple of months, my fuel mileage in Indy has dropped from around 14-15 mpg to 11-12 mpg - it does it every winter, then goes back up in the spring.

 

I live in Santa Barbara. The last trips have been up to the central coast, Big Sur area. The fuel mix could be something, although I drive a car during the week and I have not seen a corresponding drop in the car's mileage.