New tires, would like to regear to compensate

4999 Views 18 Replies 6 Participants Last post by Rockstarrchevy81, Sep 1, 2011

bluavalancheZ71

Discussion Starter · Aug 30, 2011

I have a 2010 silverado 1500 with the 5.3L and the 6 speed, and the 3.08 gear. I have recently added a lift and tires and obviously truck no longer has the grunt off the line like it did. I know I need to change gear to fix this small issue, I would like to know which gears would be ideal for the new tires and still keep my mileage from falling thru the floor. I had the 265/65/18 tires stock, and now I am running a 305/65R18 almost exactly 2 inches taller, I know I will not get it exactly like it was but I was considering a going to 3.73's. Will they fir with my current carrier in my front diff? The rear diff should be fine. Any info would be greatly appreciated.
Thanks
Blu

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sstoner911

· #2 · Aug 30, 2011

bluavalancheZ71 said:
I have a 2010 silverado 1500 with the 5.3L and the 6 speed, and the 3.08 gear. I have recently added a lift and tires and obviously truck no longer has the grunt off the line like it did. I know I need to change gear to fix this small issue, I would like to know which gears would be ideal for the new tires and still keep my mileage from falling thru the floor. I had the 265/65/18 tires stock, and now I am running a 305/65R18 almost exactly 2 inches taller, I know I will not get it exactly like it was but I was considering a going to 3.73's. Will they fir with my current carrier in my front diff? The rear diff should be fine. Any info would be greatly appreciated.
Thanks
Blu

If this truck is 4 wheel drive you need to change both fron and rear to match. I wouldnt go any more than 3.23 with that size tire.

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sstoner911

· #5 · Aug 30, 2011

bluavalancheZ71 said:
SS, yes the truck is 4wd and since I was talking about concerns for the front diff should have been a give away . And you think a 3.23 gear is right? Or did you mean 3.73?
Thank you fleetwood, the chart helps. But 1 concern, question I have is will I need to get a new carrier for the front diff will it all fit in the case?
Since I have the 6 speed and reading the other posts about this I'm really considering going to the 4.11's and calling it a day

ya I want sure if you had a 4x4 since you were talking about keeping the rear the same.....with a 18 inch tire 4.11 may bring your rpm to high at freeway speeds.

---------- Post added at 08:37 AM ---------- Previous post was at 08:08 AM ----------

I have 4.11 with 32 inch tall tires..at 65mph my rpms at 65mph are 2200 , at 85 they run 2500rpm.

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sstoner911

· #7 · Aug 30, 2011

Wait..i mis read your post..how tall[HR][/HR] is the new tire?

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sstoner911

· #10 · Aug 30, 2011

Ok...4.11 or maybe even 4.56 would be ok..... 4.11 for sure.

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sstoner911

· #14 · Aug 31, 2011

Blackout07 said:
4.10. 56's would be way too steep with the 6 spd. Most charts out there do not take into consideration the ratios of the newer 6 spd transmissions. You have an 8.5" 10 bolt.

I have the same transmission and with 8.5 / 10 bolt.....you be surprised how effecient the Od is! Everyone told me I would be pushing 3000 RPMs with the 4.11 @ 75MPH.....at 85 I am just hitting 2500 rpms....the truck isnt even working hard at that range.

Depending on how much freeway driving he does I think 4.56 would be fine.

I used this calculator when figuring my new gears and it was pretty much dead on. I use .70 for the OD ratio...

http://www.rearendparts.com/pages.php?pageid=16

With 4.56 @ 80MPH it puts him at about 2500 RPM.......his engine can take that all day long.

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