Bigger Tires and Gas Mileage
#1
12-08-2000, 10:15 PM
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Location: Greensboro, NC, USA
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Bigger Tires and Gas Mileage
I am considering replacing the stock 255s on my 97 expy with 265/75/16s. Aside from the speedo issue, my local Ford dealer told that installing larger than stock tires would throw my fuel management system off significantly. To which I replied, "well - maybe mine is broken because the mileage sucks now. I get about 12-13 in the city and nearly 16.5 on the road. I didn't buy it for its fuel efficiency, but I also don't want to significantly decrease the mileage if I can help it. Any feedback would be appreciated. Thank you.
97 XLT EXPY 4.6L 4x4 3.55 gears 255/70/16 Bridgestone Dueler AT, KN Air Filter, Superchip.
97 XLT EXPY 4.6L 4x4 3.55 gears 255/70/16 Bridgestone Dueler AT, KN Air Filter, Superchip.
#2
12-08-2000, 10:29 PM
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Location: SAN ANTONIO,TEXAS,USA
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The difference is so small you wont even notice it with those tires....My neighbor has put my old tires on his truck and he says no notice in mileage.......I never did either.....I dont even feel the difference with 315s..I am sure there is but not enough for me to worry about it.....go for it.Dave
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1998 F-150, SC/Flairside,oxford white 4x2,4.6,auto,3.55s,nerf bars,cls 111 towing,bed liner w/mat,Eagle polished wheels 16x10 w/Yokahama Geolandars 315/75/16s,all plastics guards/bug shields,air raid/k & n filter, superchipped, duals out the back corners, flow master 3 chamber, snug top lid, f-150 online sticker back window-honk if you see me!!! Fabtech 3 1/2 lift,3" spindles, 3" body lift=9 1/2 inches of lift, lift lips.coverking dash cover, Lumi Logo's (front and rear), clear front corner lenses, muth mirrors,dash mounted CB, (TX Chapter requirement,lol),personalized license plates, Superlift traction bars,Image tail light covers (painted).and it still fits in the garage, yeahhhhhh
San Antonio
DWESSELS89@AOL.COM
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1998 F-150, SC/Flairside,oxford white 4x2,4.6,auto,3.55s,nerf bars,cls 111 towing,bed liner w/mat,Eagle polished wheels 16x10 w/Yokahama Geolandars 315/75/16s,all plastics guards/bug shields,air raid/k & n filter, superchipped, duals out the back corners, flow master 3 chamber, snug top lid, f-150 online sticker back window-honk if you see me!!! Fabtech 3 1/2 lift,3" spindles, 3" body lift=9 1/2 inches of lift, lift lips.coverking dash cover, Lumi Logo's (front and rear), clear front corner lenses, muth mirrors,dash mounted CB, (TX Chapter requirement,lol),personalized license plates, Superlift traction bars,Image tail light covers (painted).and it still fits in the garage, yeahhhhhh
San Antonio
DWESSELS89@AOL.COM
#3
12-09-2000, 12:46 AM
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Physically speaking there will be a difference because of the difference in diameters. That you will notice it or not is another thing.
If you do a lot of highway it will help since the larger diameter tire will cover more distance than the smaller tire in one revolution. The engine will be running at less RPM's at the same speed. Less RPM's better mileage. But it will have to do a lot of effort in breaking the inertia of the standing vehicle. So, if you have a heavy right foot the vehicle will be more sensitive to gas consumption. All in all it depends on the variables out there to get back to your original MPG provided that you are using now the correct speedo gear.
In my case I went from 31.6" tires to 34.6" diameter tires. Now the truck is consuming a little bit more of gas. I did change the speedo gear and I will be doing the gear swap (to 4.56:1) sometime next year. We have to consider that the tires have a larger frontal area (more resistance to the wind), wider stance (more friction with the ground) and larger overall size (more weight), and to deal with all this you need more energy.
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My Ride: 1998 F150 4x4 Lariat Supercab Flareside 5.4L in Oxford White/gold, ORP, Tow Package, 3.55 Gears.
Modifications: K&N FIPK, Stepshield door sill protectors, Performance Accesories 3" body lift, Lift Lips, Gabriel Gas Ryder LT VST Shocks, Daystar front anti-sway bar polyurethane bushings and 35x12.5R16.5LT BFG All Terrain KO's on 16.5x9.75 American Eagle 589's.
Photos at: http://www.communicomgroup.com/jmtruck
[This message has been edited by JMTruck (edited 12-09-2000).]
If you do a lot of highway it will help since the larger diameter tire will cover more distance than the smaller tire in one revolution. The engine will be running at less RPM's at the same speed. Less RPM's better mileage. But it will have to do a lot of effort in breaking the inertia of the standing vehicle. So, if you have a heavy right foot the vehicle will be more sensitive to gas consumption. All in all it depends on the variables out there to get back to your original MPG provided that you are using now the correct speedo gear.
In my case I went from 31.6" tires to 34.6" diameter tires. Now the truck is consuming a little bit more of gas. I did change the speedo gear and I will be doing the gear swap (to 4.56:1) sometime next year. We have to consider that the tires have a larger frontal area (more resistance to the wind), wider stance (more friction with the ground) and larger overall size (more weight), and to deal with all this you need more energy.
------------------
My Ride: 1998 F150 4x4 Lariat Supercab Flareside 5.4L in Oxford White/gold, ORP, Tow Package, 3.55 Gears.
Modifications: K&N FIPK, Stepshield door sill protectors, Performance Accesories 3" body lift, Lift Lips, Gabriel Gas Ryder LT VST Shocks, Daystar front anti-sway bar polyurethane bushings and 35x12.5R16.5LT BFG All Terrain KO's on 16.5x9.75 American Eagle 589's.
Photos at: http://www.communicomgroup.com/jmtruck
[This message has been edited by JMTruck (edited 12-09-2000).]