Lots of questions on tire size - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > General Jeep Discussions > Tires & Wheels

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 03-17-2013, 11:14 PM   #1
Jeeper
 
bevensen's Avatar
 
Join Date: Jan 2013
Location: New York
Posts: 24
Lots of questions on tire size

I just recently put a 2.5 inch Teraflex spring lift on my two door 2010 Islander. I am still sitting on my 32 inch Rubicon tires unfortunately. I am planning on getting new tires to complete the look of my jeep. However, I am stuck on what size I should go for. This is my DD and I commute 50 miles daily. I would love to go for either 35s or 34s- which are 315/70/R17 or 305/70/R17, correct me if I am wrong. I know I shouldn't expect great MPG with a Jeep, but I do want to be realistic with the cost of gas . I am assuming there would be a minimal difference in MPG between these two size choices. Would an All-Terrain tire give me noticeable better MPG than a mud terrain tire? I would like to keep my stock tire carrier as well if possible. Any help is appreciated.
Click image for larger version

Name:	IMG_20130310_161111.jpg
Views:	152
Size:	223.3 KB
ID:	224217

bevensen is offline   Quote Quick Reply
Old 03-18-2013, 07:01 AM   #2
Jeeper

WF Supporting Member
 
kbwwolf's Avatar
 
Join Date: Sep 2011
Location: Wisconsin
Posts: 12,179
Quote:
Originally Posted by bevensen View Post
I just recently put a 2.5 inch Teraflex spring lift on my two door 2010 Islander.
This is my DD and I commute 50 miles daily. I would love to go for either 35s or 34s- which are 315/70/R17 or 305/70/R17.
I am assuming there would be a minimal difference in MPG between these two size choices.
First, just so you know, the 315s are probably true 34" tires; the 305s are more like 33".

You're correct about the MPG difference. However, you'll have a bigger issue with your gearing. The 3.8L Jeeps (07-11) come from the factory terribly undergeared. The larger and heavier tire you run on em, the more power you'll lose at the top end. This will be worse with an automatic than it will be with a manual. You'll find that you won't be able to use high gear to pass on the freeway, to go up hills, or even, in some cases, when there's a stiff headwind. The only real fix for this is to regear, which costs ~$1500.

A lot of peeps mitigate this somewhat by going to a smaller wheel (15" or 16" instead of 17" or 18", which also saves $$ on tire costs). Also, the lighter the tire/wheel combo you run, the better off you'll be.

Quote:
Originally Posted by bevensen View Post
Would an All-Terrain tire give me noticeable better MPG than a mud terrain tire?
Yes. It'll last longer on-road, as well, and in most cases will be quieter.

Quote:
Originally Posted by bevensen View Post
I would like to keep my stock tire carrier as well if possible.
Then stay away from the 315 size.

__________________


"What we see depends mainly on what we look for."
—John Lubbock
kbwwolf is offline   Quote Quick Reply
Old 03-18-2013, 12:38 PM   #3
Jeeper
 
Jakemac's Avatar
 
Join Date: Oct 2012
Location: Lancaster, NY
Posts: 161
I went from the 31s on mine to 35s... The MPG for me dropped 1 mpg. Hills are interesting with a manual trans. for an auto i can promise you your MPG will suck cause the jeep will want to run on 2nd gear up a hill at 50mph. On mine i can crawl up decent hill at 55 in 4th and maintain about 3k RPM runnin on 3.11 gears. The amount of change from the 31s to the 35s is noticeable but i wasnt bugged by it at all. The acceleration on flat ground is the exact same and the hilss you need to down shift a little more. I doubt i'll get sick of it tho. Mind you a lot of people are going to say im nuts or the gearing is way to low, or try to sway you otherwise. You wont really know until you put them on though.
__________________
________
l l ,[___], trololololoooool
l---- L -OlllllllO-
()_) ()_)--o--)_)
Jakemac is offline   Quote Quick Reply
Old 03-18-2013, 04:00 PM   #4
Jeeper
 
bevensen's Avatar
 
Join Date: Jan 2013
Location: New York
Posts: 24
Quote:
Originally Posted by Jakemac View Post
I went from the 31s on mine to 35s... The MPG for me dropped 1 mpg. Hills are interesting with a manual trans. for an auto i can promise you your MPG will suck cause the jeep will want to run on 2nd gear up a hill at 50mph. On mine i can crawl up decent hill at 55 in 4th and maintain about 3k RPM runnin on 3.11 gears. The amount of change from the 31s to the 35s is noticeable but i wasnt bugged by it at all. The acceleration on flat ground is the exact same and the hilss you need to down shift a little more. I doubt i'll get sick of it tho. Mind you a lot of people are going to say im nuts or the gearing is way to low, or try to sway you otherwise. You wont really know until you put them on though.
I have an automatic with 3.73s. The problem with going with larger tires on these gears is just the increased weight, correct? The stock rubicon tires weigh about 48 pounds. The tires I am looking at are Duratrac 315/70R17. They weigh 60 pounds according to Tirerack.com. Do you think I would be bogged down running these tires?
bevensen is offline   Quote Quick Reply
Old 03-19-2013, 07:42 AM   #5
Jeeper
 
Jakemac's Avatar
 
Join Date: Oct 2012
Location: Lancaster, NY
Posts: 161
If you were to add 10 lbs to your current body weight and went about your normal day would you feel bogged down? Its no different then putting a bigger tire on the rear tailgate. Its only 10 lbs unless you plan on jumping it, its really not that big a deal
__________________
________
l l ,[___], trololololoooool
l---- L -OlllllllO-
()_) ()_)--o--)_)
Jakemac is offline   Quote Quick Reply
Old 03-20-2013, 03:32 PM   #6
Jeeper
 
Join Date: Jul 2010
Location: Long Island
Posts: 21
Brandon if I was you I would get either the procal or a tuner and go with a 35 or a 34 inch tire. Drive it and see how you like it. With 3.73s you might not be all that bad. But I would start saving for gears. I just did mine and it's night and day difference

__________________
2012 2 Door Sport S 6 Speed
3inch BDS w/ Bilstein 5100s
Fierce Attitude 35s
4.56 with truetrac in the rear
cam36 is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 01:53 PM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC