[trentpierce]

I've owned my Accord for a year and 42k miles and have been reading this and other forums daily all along. Finally joined! I've been running the stock Hankook Kinergy tires that my LX came with for the first 42k and have been getting AMAZING fuel economy. I drive around 150 miles per day almost all highway varying speed limits about 50% 60 mph and 50% 70 mph. For the whole first set of tires I could maintain 40 mpg without even thinking about it, actually better when not in ECON mode. If I concentrated on my driving i could easily have a 45 MPG tank average. Now that I have my new tires, Firestone Firehawk AS, my fuel economy has plummeted. I have put about 1000 miles on the new tires and have averaged 35 mpg on each of the two tanks of gas, and it has been a hard fight to keep it that high! I'm not really complaining as i'm still above the city/highway combination my window sticker showed by a good bit. I'm more surprised at how much this set of tires has dropped my economy. Has anyone else experienced this sort of 10%-20%+ change in economy at a tire change?

Just for reference, my car has always achieved the best mileage with Murphy USA walmart gas 87 octane and I have run it almost exclusively because its $1.47/gallon locally!

2019 Accord LX 1.5 CVT

Just a food for though post for everyone. Thank you to everyone for all the good advice over the last year even though you didn't know I was lurking!

 

[Samuelx]

Assuming everything else is the same - maybe the Firestones are just heavier and/or get better MPG at a different tire pressure?

 

[trentpierce]

I also thought about tire weight but can't find anywhere that states the weights, i'm running them at the same 32 psi pressure. I also wondered if may my "efficient" speeds have shifted. I'm going to try driving a few MPH slower and faster to see.

 

[trentpierce]

After some google foo, it looks like the firestones are in fact about 3.5lbs heavier than the hankooks. Still i just can't imagine it making so large a difference. Its more interesting than anything, still quite happy with the economy. My previous car was a 5.6l Armada so this is still like floating on a cloud.

 

[jninja]

Well, you can easily offset heavier tires with aftermarket wheels...you can save as much as 15-20 lbs PER wheel by ditching the heavy AF Oem wheels. Although I wouldn’t buy new wheels solely for MPG- it is a nice side effect. I switched to 19” Koenig from 19” oem sports and saved around 60lbs total iirc...better handling, performance, looks, etc

 

[trentpierce]

Well, you can easily offset heavier tires with aftermarket wheels...you can save as much as 15-20 lbs PER wheel by ditching the heavy AF Oem wheels. Although I wouldn’t buy new wheels solely for MPG- it is a nice side effect. I switched to 19” Koenig from 19” oem sports and saved around 60lbs total iirc...better handling, performance, looks, etc

Good idea! I wonder how the heavy AF oem 17"'s compare in weight to the heavy AF oem 19" wheels. I would love to have the stock 19's but fear they weigh even more. And I've read that moving the weight further from the axis of rotation will make the effect even more pronounced. For my needs a similar diameter lighter wheel would be ideal. Especially considering i just bought a set of 17" tires. haha. Reading over fuel economy posts I feel like i was was in the minority regularly getting mid 40's.

 

[jninja]

Good idea! I wonder how the heavy AF oem 17"'s compare in weight to the heavy AF oem 19" wheels. I would love to have the stock 19's but fear they weigh even more. And I've read that moving the weight further from the axis of rotation will make the effect even more pronounced. For my needs a similar diameter lighter wheel would be ideal. Especially considering i just bought a set of 17" tires. haha. Reading over fuel economy posts I feel like i was was in the minority regularly getting mid 40's.

Yeah I’m not sure what all the wheel weights are for oem- but I believe the “sport” 19” wheels are about 44lbs ea...my 19” Koenig were about 25lbs ea. I believe you can get under 20lbs each with the right set of 17” wheels...huge difference in performance ditching the extra rotational weight

 

[trentpierce]

Follow up:
I was questioning the alignment of the tires. It really felt like I was dragging a cinder block behind me. I had planned on going back to Firestone to have them double check my alignment yesterday. Well life solidified that decision for me when i had to move onto the shoulder to let an ambulance pass me Wednesday night. Wham! hit a pot hole and blew my front right tire. Man isn't that 2020! less that 500 miles on these tires and I blow one up.

So the reason for the follow up, I was able to get the tire warrantied, thank goodness for road hazard coverage! They realigned the car because of the pot hole impact. They said the rear toe was WAY out.

This morning, the first drive to work since the alignment I averaged 43.3 MPG and my tank average climbed over 39 mpg. I think i'll easily exceed 40 mpg on this tank average if this continues.

I know a single trip a tank average does not make so i'll post another update after 2 more tanks of fuel.

I really think my first alignment was not done properly and that caused all of my fuel economy drop. Time will tell!