Tire size and Fuel Consumption

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kup99

kup99

10 Year 15 Year
Joined
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Calgary Alberta Canada
hey gang, I am posting this in this section because I wnat the response from the diesel heads out there. Looking to upgrade my tires!! I am thinking 33"s I will be doning a little of mild wheeling, but mostly street as this is my dd. I don't have any lift, and am not sure if I am going to put one on as not to kill fuel milage. I am wondering:

1. What kind and size of tires are you running and you opinion of them?

2. What have you noticed about your fuel milage since the tire swap? assuming that you went bigger!!

Thanks for the help Guys,
:idea:
 
I swapped my 33 and 31 between the 75 and the 73 series. No discernable difference in fuel consumption.
The 31s give them a bit more speed on take off and the 33 cruise along nicer at highway speeds
This is with 1HZs,so with a 1HD T I dont think you will notice the power difference too much.

I thought the stock tyres on a 80 series were close to 33 anyway.
 
I went from 31 to 33 BFG and really like them.

The only complaint is from my Grandmother. She noticed the height difference climbing in with her bad hip.

If you are looking for some BFG 33x12.5 r 15 I know someone in Edmonton selling 4.

:cheers:

Todd
 
with a 16" rim, what measurement would give me a 33" tire??
 
kup99 said:
with a 16" rim, what measurement would give me a 33" tire??
Click to expand...

255 85 16

That's what I'm running right now and my GPS corrected fuel economy is about the same as with 31s (but my revs are much lower for any given speed - need to address that sometime soon).
 
what type of tire did you guys go to M/T A/T ?? thanks, also how much are you on the road and how much offroad.. thks
 
I recently replaced my 31s for 33x9.5. She rolls much smoother and gets over the big stuff a bit better. Traction is much better too but that may have to do with the tire design as much as shape. Right now fuel economy seems to be 22-23 mpg with 33s and 3' of lift.
 
275/__?/16 will give me a 33" tire??
 
kup99 said:
275/__?/16 will give me a 33" tire??
Click to expand...



The math to do the caculation is easy:

first, take the section width (the number that appears first - 285), then multiply that by the aspect ratio - usually 75 or 85 in truck tires. It's the height of the sidewall as a percent of the section width. So, if you have a 285 75R 16 you will have section height of 285mm x .75 = 213.75mm.

To calculate the overall height of the tire you add: [ rim diameter in inches + 2(section height)/25.4 = overall height (give or take a little dependent on the manufacturer).

So your 285 75 R16 is 16"

16" + 2(213.75)/25.4 = 16" + 16.83" = 32.83" with a section of 285mm (11.22")

The section width is NOT tread width. It is the width across the widest part of the tire casing.

a 255 85 R16 gives ---> 16" + 17.07" = 33.07" (in reality they are about 33.5", but that also is a factor of rim width to a small degree)


A typical 15" rimmed tire is a fair bit shorter than it's advertised height.

16" rimmed tires using the P-metric system are pretty close to the calculated heights on the correct rims of the tire size.

16" tires usually run at much higher pressures than the equivalent 15" tire and, as such, have quite a bit less rolling resistance (= fuel savings ). The 16" casing is also usually a lot stronger than the equivalent 15" casing - as evidenced by load ratings and ply ratings.

hth, and ymwv.

~John
 
If your not installing a lift, stick with 285/75R16. A friend of mine just put the Nokian all terrains on his HDJ81 in Calgary and loves them. This is very close to 33" tires and you shouldnt notice a power differince from you POWERFULL 1HD-T
 
I am running 33x9.5 15 bfg at ko's , 2.5 inch OME , city fuel millage has dropped a bit , i blame it on the gearing i will put some lower gearing in to get back closer to stock gearing , if you dont have a lot of hills to get up and go around get the 33's , if you do in the end you will likley decide you want to re gear any way , if you put the 33's on they will fit on the stock suspension but look a bit silly , if your not going with a lift and doing gears stick with 31x10.5 's , the bfg at ko's are a kick ass tire and i got mine for $176 a piece .
 
before and after pics
on33's.webp
 
Generally, going to larger tires results in lower fuel economy. I have run 255-85-16's and am now running E load 285 75 16's which are exactly 33". Calculations are close but actually measuring tires will show some deviation from calculated values. My fuel consumption has ranged from a low of about 11 l / 100 km to a high of 15.5 l / 100 km (heavy snow, 100% short trip driving). My avg fuel consumption to date over about 15,000 km is 13.39 l / 100 km running Stanadyne Performance Plus additive and corrected using GPS.
 
It depends if you match taller tires with correct gears .. I thought 285 ( similar 33" ) tires are nice size for 1HD-T engines in 80 series .. more result in poor economy and less higer rpm that finaly means poor fuel economy also ..
 
wish I could JDM ... wish I could.. I might be interested in your rims though?? let me know if you are going to move on them.!!.
 
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