Jeep Wrangler Forum

Jeep Wrangler Forum (http://www.wranglerforum.com/)
-   JK General Discussion Forum (http://www.wranglerforum.com/f274/)
-   -   Actual Mileage on Actual tire size (http://www.wranglerforum.com/f274/actual-mileage-on-actual-tire-size-142663.html)

pkmcd99 02-27-2012 04:01 PM

Actual Mileage on Actual tire size
 
I hear alot of beef about gas mileage and power lost on 3:73 gears with bigger tires. Are you refering to actual size of tire or printed size on side wall? Wondering? Most 285/75r16 are not 33", there similar to stock 32" tires....etc many combos. Another would be the 35" tires that most have purchased such as 315/75r15 that are around 34" in most cases. Im serious about honest experience, as im considering a true 34" tire such as 315/75r16

kjeeper10 02-27-2012 04:53 PM

Quote:

Originally Posted by pkmcd99
I hear alot of beef about gas mileage and power lost on 3:73 gears with bigger tires. Are you refering to actual size of tire or printed size on side wall? Wondering? Most 285/75r16 are not 33", there similar to stock 32" tires....etc many combos. Another would be the 35" tires that most have purchased such as 315/75r15 that are around 34" in most cases. Im serious about honest experience, as im considering a true 34" tire such as 315/75r16

Ya but the stock 32's are actually 31 (ish)
So you are still moving up a size when you go 33" which is around a 32" mounted.

Confusing :)

pkmcd99 02-27-2012 05:04 PM

Quote:

Originally Posted by kjeeper10

Ya but the stock 32's are actually 31 (ish)
So you are still moving up a size when you go 33" which is around a 32" mounted.

Confusing :)

Good point :very confused also now:

Sparkplugg 02-27-2012 05:21 PM

Most of the time, the tire's actual size is just slightly smaller than that stated size. The difference is usually less than an inch. The variables are wheel mounting and tire pressure.

kbwwolf 02-27-2012 05:23 PM

Quote:

Originally Posted by pkmcd99 (Post 2080448)
I hear alot of beef about gas mileage and power lost on 3:73 gears with bigger tires. Are you refering to actual size of tire or printed size on side wall? Wondering? Most 285/75r16 are not 33", there similar to stock 32" tires....etc many combos. Another would be the 35" tires that most have purchased such as 315/75r15 that are around 34" in most cases. Im serious about honest experience, as im considering a true 34" tire such as 315/75r16

I went from stock tires to 315/75R16's, and lost ~ 3 mpg. Also suffered some power loss, most noticeable in high gear on the freeway. I have to downshift to 5th (I've got a manual) to pass or to go up long hills at highway speeds.

That's in a '12. With earlier year models the power loss will be more pronounced.

I'm gonna regear to 4.56 or 4.88's in a couple months...haven't decided which one I'm gonna do yet. If done right, that'll recover a little bit of my lost mileage, since the Jeep won't have to work as hard to maintain appropriate highway speeds.

And the power loss will be no more. :D

Sparkplugg 02-27-2012 05:29 PM

I have the same setup as Wolf. With 4.10, I prefer the way mine drives on the road better now than before the addition.

pkmcd99 02-27-2012 05:54 PM

Quote:

Originally Posted by Sparkplugg
Most of the time, the tire's actual size is just slightly smaller than that stated size. The difference is usually less than an inch. The variables are wheel mounting and tire pressure.

Sometimes, but im refering to the cause related to tread depth from the factory.

JIMBOX 02-27-2012 06:10 PM

:whistling: I went from tire size 32" and 4.10 gears/ 15.2 mpg to-

Tire size 33.2" and 5.38 gears/17.2 mpg-

It's all relative jeepers--all relative !

:dance::rofl: JIMBO

rics1997 02-27-2012 06:11 PM

The thing is compression. If you were 4 rubber balloons filled with air and had to hold up a 4000lb vehicle, see if you could hold your shape. If you add 65psi verses 30psi there probably would be a big difference too. The only number that matters when figuring final ratio with the tire is the number from the center of the wheel to the road and there is were the compression takes place.

rics1997 02-27-2012 06:14 PM

Also, gas mileage changes are also not only from going up a tire size but almost more important is tire weight. The stock tires that come on a Jeep are actually fairly light. Especially the Goodyear SRA's. Thats one of the reasons they use that tire. Most mud tires that many go to are heavy tires and weight kills mileage.

jplks2play 02-27-2012 06:22 PM

I went from the stock wheels and tires to 15s and a 35 inch tire. No regear yet. I'm going to a 4.88. I have lost 2mpg. Not a tremendous loss concidering I was only getting 12 in my yj. As for power I have yet to feel the difference. But I don't drive on the highway that much. And my tire psi is at 35. I know its high. Setting it to 28.

rics1997 02-27-2012 06:28 PM

You will get better gas mileage at 35 psi, You will get a softer ride at 28 PSI. Not sure what tire you have but 28 psi is a littler low IMO but shouldn't be too much a problem if it's a C class tire but 30 psi probably would be better. Itf it is a D or E class tire it should be at 32 to 35 psi.

jplks2play 02-27-2012 06:33 PM

It's a kuhmo mt e class. Thanks for the info.

Dick Blonov 02-27-2012 08:32 PM

Quote:

Originally Posted by pkmcd99 (Post 2080660)
Good point :very confused also now:

Allow me to add to the confusion :)

If you look at the revs per mile figure, you get a more realistic value:

A stock LT255/75 R17 BFG mud terrain comes out to 31 inches (650 revs per mile according to BFG) although it's listed as a 32 inch tire. The stock Sahara P255/70 R18 is very close (653 revs per mile).


So a GY DT LT285/75 R16 is in fact 31.8 inches (@634 revs per mile) although it is listed at 33.1 inches.


DB

Dick Blonov 02-27-2012 09:05 PM

Quote:

Originally Posted by Dick Blonov (Post 2081633)
Allow me to add to the confusion :)

If you look at the revs per mile figure, you get a more realistic value:

A stock LT255/75 R17 BFG mud terrain comes out to 31 inches (650 revs per mile according to BFG) although it's listed as a 32 inch tire. The stock Sahara P255/70 R18 is very close (653 revs per mile).


So a GY DT LT285/75 R16 is in fact 31.8 inches (@634 revs per mile) although it is listed at 33.1 inches.


DB

As stated here!

Quote:

Originally Posted by kjeeper10 (Post 2080626)
Ya but the stock 32's are actually 31 (ish)
So you are still moving up a size when you go 33" which is around a 32" mounted.

Confusing :)


DB

Jedi6 02-28-2012 08:27 AM

I went from JKU Sport stock to 285/70/17 Duratracs and lost about 2 mpg. No loss of power that I can tell with the 3.73 auto trans.

4fit 02-28-2012 08:34 AM

Lost about 1.5mpg going from stock 255/75/17 SRA (measured 31.2") to 285/75/16 Falken Rocky Mountain ATS (measure 32.3") with 3.73s in my '11. I now average about 16.7. Used to hover in the low 18s.


All times are GMT -5. The time now is 03:18 AM.