Pissed off about MPG after new tires

That’s due to air density and temperature... not a change in gravitational force (well aside from if you spend all your time coasting down a mountain)

 

You would have to be fighting a pretty strong pull all the time to have an alignment bad enough to kill your MPGs that much. I've had bad alignments plenty of times after wheeling trips and never really had much of an MPG difference, not enough to make me notice it anyway.

But I could definitely see an alignment being the issue if you're getting pulled to one side pretty good and having to constantly correct it or hold the wheel to keep it straight.

 

yeah, if it’s out of whack you can tell but I just put 285’s on my truck and they couldn’t do alignment cause of cams being stuck. I had to drive it like 20 miles home to cut them off and replace. I drove the 20 miles back and used like 1/2 a tank cause the toe was in on both wheels and basically pushing all the way down the road. Only time you could tell was at a stop when it wouldn’t roll down a hill at all.

 

I think someone siphoned your gas, lol. I can't imagine even dragging a ship anchor would cause you loose half a tank in 40 miles. That's like 5mpg.

 

well I did drive around the neighborhood a little to show off the wheels on my beater but it wasn’t much. Lol. I prob ended up putting like 3k mileage on tires though. They looked worn compared to rears. I only got like 320 miles per tank before tires. Prob looking at like 250 w these ones. Idc though. It’s not a daily driver. Got the 3rd gen for that.

 

I don't think I've EVER gotten 320 miles from a tank.

My 2004 isn't a daily driver either, but I've typically gotten 220 or so out of a tank in the city. Always seems like I was filling it up around 200-220 when I was commuting with it. I might approach 300 it it's all highway. Although most of my road trips I was usually towing a <3k pound trailer, which brought me back down to ~220 mile range.

In Oct I'm heading to Moab, which is I think the first time I've actually driven that far without towing a trailer that I can remember, though I'll still be loaded with camping stuff. We'll see what my MPGs are then...

 

How many miles you get per tank is next to useless info. How many miles per gallon? Give us real numbers to compare, and if you don't know what the mpg was with the old tires you have nothing to compare to.

Lots of stuff going on here.

#1 Mixing 2 old tires along with 2 new tires is not a good idea. Especially if you have a 4X4. If you do, do not operate in 4X4 until you have a matched set of tires all around. Even if you bought the same size and same brand the old tires are going to be roughly 1 size smaller than they were when new. The difference can be even greater when you start mixing different brand tires.

Which axle are the new tires on? If the new tires are on the rear your odometer is now going to be reading fewer miles than before since the new tires are larger in diameter and need fewer revolutions to go a mile.

Your speedometer is now off too. If you think you're driving 70 mph, and are actually driving 75 you'll take a big hit in fuel mileage. I've found that at 60-65 MPG's are great. Up to 70mph and they are acceptable. But above 70 mph and fuel mileage takes a huge hit in my Tacoma.

#2 The tires weight has much less to do with MPG's than internet lore. I went from a 38 lb tire to a 53 lb LT tire on my Tacoma and fuel mileage is exactly the same as before. Of course the new tires are the same size and with a similar mild AT tread. Going to a wider tire, a taller tire, and a tire with a more aggressive tread will cost you 2-3 mpg. Not having the proper tire inflation can cost you 2-3 mpg.

I had a similar weight gain when I went to E rated tires on my F150. I lost just over 1 mpg, but changed to a taller tire with a more aggressive tread. The extra 15 lbs per tire had little if anything to do with it.


#3 Gas matters. Most are going to winter gas now and that can make a difference in fuel mileage. Also I've gotten a tank of gas from time to time that simply didn't give me the power or fuel mileage I expected. It happens and I don't know why. If you're basing this on only 1 tank of gas it may be too early to blame the tires.

 

pretty much same. The only time I actually reset it was when I had the pizza cutters and no ac on a trip like 2 hrs away. Cruised like 65 the whole way there and back rest was light cruising around town no lights. Ended up 315 on that tank but she was on fumes when I ended up filling tank.