Re-gear, When?

[chill]

So at what point in increased tire size do we need to re-gear to accommodate? And to the next point what gear to what tire size? Are there any other reasons to upgrade the gears other than increased tire size?

 

[tjkj2002]

When going to 245/75R16's(or simliar size) 4.10's are recommended,must for 265/75R16's(or similar size) but 4.56's would be best for 265/75R16's but that would require JBA's steel front diff conversion.

 

[Dave]

Just as a comparison.....I am running 245/70/17's and my OEM stock size was 235/65/17. I notice a loss of power and about 200 rpm drop at speed. The ****** shift points are off a little. I usually just leave O/D locked out until I get to highway speeds. My torque converter locks/unlocks now in the mountains at different speeds so I have to compensate with locking out O/D more often. So looks like I need 4:10 gears now.



Dave

ps.....speedo is off too..

 

[chill]

Okay then. Glad I asked. I am getting 245/70/17's. I posted in the off chance that it might be a good idea. Speedo is going to be re-calibrated soon after anyway as I saw that one coming. You meant 2000 revs I guess. That concerns me a bit.
Here a question though. 4.10's just slide right in, or am I worried about PCM issues, and the like? and oh yes mpg's as is usually the case, right?

 

[Dave]

Okay then. Glad I asked. I am getting 245/70/17's. I posted in the off chance that it might be a good idea. Speedo is going to be re-calibrated soon after anyway as I saw that one coming. You meant 2000 revs I guess. That concerns me a bit.
Here a question though. 4.10's just slide right in, or am I worried about PCM issues, and the like? and oh yes mpg's as is usually the case, right?

No, 200rpms. (approx)

Dave

 

[TwoBobsKJ]

Okay then. Glad I asked. I am getting 245/70/17's. I posted in the off chance that it might be a good idea. Speedo is going to be re-calibrated soon after anyway as I saw that one coming. You meant 2000 revs I guess. That concerns me a bit.
Here a question though. 4.10's just slide right in, or am I worried about PCM issues, and the like? and oh yes mpg's as is usually the case, right?

If you regear at the same or close to the same time as the new rubber you probably won't notice a difference. But if you drive for any length of time with the new tires before you regear - yep, you'll notice that the mileage drops and "giddyup" goes away. Regearing when you go to larger tires actually gets mileage back up to stock or better.

Bob

 

[tjkj2002]

Regearing when you go to larger tires actually gets mileage back up to stock or better.

Bob

Well may get you close to stock,will never get better but that is teh way it is due to the tires themselfs.

 

[NJallDAY]

So if im at 235/70/16 and i plan on going up a size to 245/70/16 should i put serious consideration into re gearing? I could have sworn 245/70/16 was just on threshold.

 

[tommudd]

So if im at 235/70/16 and i plan on going up a size to 245/70/16 should i put serious consideration into re gearing? I could have sworn 245/70/16 was just on threshold.

245-70s are not that much of a jump
245-75s then yes

 

[NJallDAY]

245-70s are not that much of a jump
245-75s then yes

Gotcha

 

[chill]

FYI...
Tires installed, Speedo re calibrated, Hypertech re flashed...
All is good. No noticeable issues and shifts great at the right times.
I'm happy:big_banana_Dance: