jQuery not supported.



How to determine proper gear ratios

How to determine proper gear ratios

Postby Luke300zx [OP] » Mar 09 2012, 3:27am

Hey everyone,

Got a new lift kit and want to throw on bigger tires but don't want to lose to many mpgs or put strain on your transmission? Want more offroading power? Look no further! Read this guide and you will know or at least have a very good idea what gears you would need to achieve that.

Method:

Old Tire Size: 31"
New Tire Size: 35"
Old Gear Ratio: 3.42

New Gear Ratio = (New Tire Size/Old Tire Size) * Current Gear Ratio

3.86 = (35/31) * 3.42

Since there is no 3.8 for our trucks 3.73 would be the closest thing but to compensate for the added weight of offroad tires/wheels I would go with a 4.10 to be safe.

For my personal truck I currently have 3.42's with a 31" tire, but since I tow and am soon going to get a heavy toy hauler I wanted more towing power. My plans are a 6" lift with 35" tires and I'm going with the 4.56 gears and here's why:

(35/31) * 3.42 = 3.86 (We'll say 3.73 since that's the closest), So a 3.73 would return me to stock which is not good enough since I'm going to be towing more weight on my tires and on my tow hitch with the new trailer. I want to make my truck equivalent to a stock truck with 4.10's and stock tires. Soo....

If I went with 4.10's it would be like having a truck with stock tires and 3.73's, so instead I'm going with 4.56's to make my truck more like a truck with stock tires and a 4.10 ratio (which was my goal to begin with).

If you have any questions about gear ratios I'd be more than happy to answer them here.
Original Poster
Luke300zx
Combustion on 2 pistons [L2]
Combustion on 2 pistons [L2]
Posts: 287
Topics: 14
Images: 3
Blogs: 1
Joined: Oct 27 2010, 9:38pm
Years of membership: 3 years of membership3 years of membership3 years of membership
Location: California
Year: 2006
Make/Model: Chevrolet Silverado
Extra Info: 1500 LT 5.3L V8
Group Membership:
Registered users
Related Topics  Gear Ratios   Speed...ratios...   How to determine your trim level   proper code readers   5.3 to Nv3500 Proper wiring harness?   What exhaust is this one? Help choosing a proper replacement   A curious crack or a proper vent hole?   Proper length spark plug wires?   proper way to replace 4L80E transmission filter gasket   Superior Gear is now Revolution Gear..   getting 35's do I need to re-gear   Gear changes   Considering a gear swap....   Gear ratio! 
Transmission/Drivetrain Sponsor
Advertise Here

Re: How to determine proper gear ratios

Postby jocko463 » Mar 09 2012, 1:50pm

Cool. And who said you would never use algebra in real life ...

Thanks for posting this. I think most guys, when they talk big tires and lifts, forget about this "little" detail.
I'm not so much a smart guy as a guy smart enough to know how to find out....
'98 Sierra SL Reg Cab Short Bed
'06 Sierra SLE Extd Cab Short Bed

Support American Manufacturing and American Workers:
www.usamade.wordpress.com
www.americanmadeyes.com
User avatar
jocko463
Combustion on 2 pistons [L2]
Combustion on 2 pistons [L2]
Posts: 217
Topics: 8
Blogs: 0
Joined: May 02 2011, 11:48pm
Years of membership: 3 years of membership3 years of membership3 years of membership
Location: Southeast USA
Year: 1998
Make/Model: GMC Sierra
Extra Info: SL Short Bed
Group Membership:
Registered users

Re: How to determine proper gear ratios

Postby Luke300zx [OP] » Mar 13 2012, 12:51am

Yeah I know I did at first....then I was like "GREAT...even MORE MONEY to spend now...."

These lifts add up fast cost wise if you think of lift + gears + cost of M/T tires.
Last edited by #32 on Sep 20 2012, 10:22pm, edited 1 time in total.
Reason: Removed quote http://www.silveradosierra.com/announcements/guidelines-for-using-the-quote-feature-properly-t259.html
Original Poster
Luke300zx
Combustion on 2 pistons [L2]
Combustion on 2 pistons [L2]
Posts: 287
Topics: 14
Images: 3
Blogs: 1
Joined: Oct 27 2010, 9:38pm
Years of membership: 3 years of membership3 years of membership3 years of membership
Location: California
Year: 2006
Make/Model: Chevrolet Silverado
Extra Info: 1500 LT 5.3L V8
Group Membership:
Registered users

Re: How to determine proper gear ratios

Postby pvoltmer » Apr 02 2012, 2:59pm

I'm going from a 31.5" tire to a 32.5" tire...I don't really need to change gears for that small of a jump do I? The numbers are close either way you go, by using your equation.

If later on I want to put on a lift kit (currently just have a leveling kit), I would probably then want to change gears, correct?
2013 Silverado 1500 Greystone Metallic
Leveling Kit
Husky Floor Liners and Mud Guards
20% tint - 5% Brow
pvoltmer
Combustion on 1 piston [L2]
Combustion on 1 piston [L2]
Posts: 198
Topics: 11
Images: 5
Blogs: 0
Joined: Feb 28 2012, 9:03pm
Years of membership: 2 years of membership2 years of membership
Location: United States
Year: 2013
Make/Model: Chevrolet Silverado
Extra Info: 1500 Z71
Group Membership:
Registered users

Re: How to determine proper gear ratios

Postby druwevr » Apr 11 2012, 10:17pm

http://www.4lo.com/calc/geartire.php go here if u need to figure out new ratio
Image
User avatar
druwevr
Armed Forces
Armed Forces
Firing on 6 cylinders [L1]
Firing on 6 cylinders [L1]
Posts: 66
Topics: 13
Images: 25
Blogs: 1
Joined: Sep 22 2011, 6:48pm
Years of membership: 2 years of membership2 years of membership
Location: Alabama
Year: 2008
Make/Model: Chevrolet Silverado
Extra Info: 1500 4.8L
Group Membership:
Registered users
Servicemen

Re: How to determine proper gear ratios

Postby Cuban. » Apr 20 2012, 4:06pm

some people dont even go by that rule.

nbs z71's come factory with 3.73's on 32.5's but this method says a 3.73 will make 35's feel stock? But i know that rule applies to the motor itself as well. Go from 3.73's and then step it to 4.56 and you'll see what you've been missing. I have 35's and 4.56's and the smaller ratio is just beyond inferior. There is so much more power and giddy-up. For 33's i recommend nothing lower than a 4.10 ratio.
Cuban.
Combustion on 1 piston [L2]
Combustion on 1 piston [L2]
Posts: 142
Topics: 1
Blogs: 0
Joined: Apr 19 2012, 6:37pm
Years of membership: 2 years of membership2 years of membership
Location: USNB Guantanamo Bay, Cuba
Year: 2000
Make/Model: Chevrolet Silverado
Group Membership:
Registered users

Re: How to determine proper gear ratios

Postby Luke300zx [OP] » Apr 21 2012, 12:11am

The only problem with the 4lo calculator is that it doesn't take into consideration for weight or rolling mass of the bigger tires. That's why even though you do the calculations and say it puts you right in the middle of 3.73 and 4.10 but you're going from say 32" to 35" I'd get the 4.10's...just because mileage difference would be very minimal and you'd have a bit more towing power if you did tow.
Original Poster
Luke300zx
Combustion on 2 pistons [L2]
Combustion on 2 pistons [L2]
Posts: 287
Topics: 14
Images: 3
Blogs: 1
Joined: Oct 27 2010, 9:38pm
Years of membership: 3 years of membership3 years of membership3 years of membership
Location: California
Year: 2006
Make/Model: Chevrolet Silverado
Extra Info: 1500 LT 5.3L V8
Group Membership:
Registered users

Re: How to determine proper gear ratios

Postby joeyride61 » May 03 2012, 12:03am

I just installed 4.56 gears today on my 4x4 2007 NBS 4x4. Soooo much better. I researched for hours on different forums about what to do. In the end, if you want the performance of a 4.10 in a 35" tire, 4.56 is the way to go - IMO.

Also, in all my research and looking at gear ratio charts, it says that I should have gone with the 4.10's too...but keep in mind that the overdrive's final ratio is less than 1:1, its more like 1:.73 or even 1:.69 according to Wikipedia. The charts all estimate based on a 3 speed transmission with a 1:1 ratio. The beauty with the OD on our trucks is it lets you run lower RPM's with a higher gear.
User avatar
joeyride61
Newbie
Newbie
Posts: 4
Images: 3
Blogs: 0
Joined: May 02 2012, 11:15pm
Years of membership: 2 years of membership2 years of membership
Location: California
Year: 2007
Make/Model: Chevrolet Silverado
Group Membership:
Registered users

Re: How to determine proper gear ratios

Postby Luke300zx [OP] » May 16 2012, 11:50pm

Does your new truck have the 4 speed or 6 speed?
Original Poster
Luke300zx
Combustion on 2 pistons [L2]
Combustion on 2 pistons [L2]
Posts: 287
Topics: 14
Images: 3
Blogs: 1
Joined: Oct 27 2010, 9:38pm
Years of membership: 3 years of membership3 years of membership3 years of membership
Location: California
Year: 2006
Make/Model: Chevrolet Silverado
Extra Info: 1500 LT 5.3L V8
Group Membership:
Registered users

Re: How to determine proper gear ratios

Postby joeyride61 » May 17 2012, 12:23am

4 Speed. I have been driving for a few weeks now and its really fun. On the highway, I am turning about 2500 RPM at 75mph...and I will probably not drive any faster than that. But in the city off of stop lights is really great. I am probably averaging around 13 city and like 14 highway at 75...but who cares. The other thing is though I have toyo 35" tires, they actually measure about 33.5" once mounted and installed, so setting a programmer to 35" tires wil be overstating the actual results. The DIC computer will also be over stated because it makes it seem like you are going faster and further than you really are, therefore giving you better average gas mileage.
User avatar
joeyride61
Newbie
Newbie
Posts: 4
Images: 3
Blogs: 0
Joined: May 02 2012, 11:15pm
Years of membership: 2 years of membership2 years of membership
Location: California
Year: 2007
Make/Model: Chevrolet Silverado
Group Membership:
Registered users
Next

Return to Transmission/Drivetrain

 

  • Similar topics
    Replies
    Views
    Last post
  • Gear Ratios
    Rear Gear Ratio
    1, 2 by lilmagoo1 » Aug 12 2011, 1:13pm
    13 Replies
    9202 Views
    User avatar
    Last post by rsollman View the latest post
    Dec 17 2012, 11:06pm
  • 6 Replies
    54 Views
    Last post by SilveradoSierra.com View the latest post
    Sep 01 2014, 12:14pm
  • Gear Ratios
    1, 2 by TBarton18 » Nov 30 2012, 4:29pm
    15 Replies
    5918 Views
    Last post by Copperhead View the latest post
    Jul 30 2014, 9:33pm
  • Gear Ratios
    by cbellew22 » Nov 10 2013, 12:13am
    6 Replies
    473 Views
    User avatar
    Last post by CT2500HD View the latest post
    Nov 10 2013, 4:13am
  • How do I determine Ring Gear?
    by ricka182 » Oct 03 2011, 5:36pm
    5 Replies
    5084 Views
    User avatar
    Last post by 6.2Silverado View the latest post
    Oct 09 2011, 1:32pm
  • Changing gear ratios...???
    WTB a GT4 rear end with 6 lug hubs
    by acbanuchi13 » Apr 26 2012, 4:16am
    2 Replies
    863 Views
    User avatar
    Last post by ASTE25 View the latest post
    Apr 26 2012, 4:30am

Common search terms

tires lift great make stock gear proper think ratios determine wheels first right thanks

It is currently Sep 01 2014, 12:14pm

  • Sponsor
Login  •  Register
SHOP TALK (Live Chat)
Transmission/Drivetrain Forum
Transmission/DrivetrainTransmission and drivetrain related components. Discuss automatic and manual trans repairs and performance or talk about driveshafts or rear-ends and differentials. Diagnostics of 4-speed, 5-speed, or even 6-speed transmissions.
To create a new topic in Transmission/Drivetrain, click this button:
Previous topic Next topic
Sitewide News Sitemaps & Feeds

Who is online

Users browsing this forum: Java [Bad bot] and 2 guests