If you changed the gearing from 4:10's to 3:42, how does drivability and characteristics of the drive change? Does it get too unruly or anything? http://www.dieselplace.com/forum/smileys/Approve.gif

How about problems with towing? http://www.dieselplace.com/forum/smileys/Cry.gif

Lastly, what besides the gears would I have to change to complete the job, like speedometer stuff?

It's going to be a gutless wonder with 3.42 gears. 3.73 would be more reasonable if you're using stock size tires. If you go much bigger than 265/75R16's I'd stick with the 4.10's.


If you tow much I'd definitely recommend sticking with the 4.10's, the 6.5 isn't exactly a torque monster!


I run 265/75R16's on my 6.5TD van (stock was 245's) and I'm pretty close to empty 99% of the time. It came stock with 3.73 gears and it has a tough time staying in OD up a lot of the climbs now, with just that small tire size change. Give it a strong headwind and it will downshift on more inclines than I like to admit.

You could go to a 255/85/16 tire. It is a tad taller than a 285/75/16 by about a half inch and wouldn't be as wide and thereby eliminating the 285's huge rolling resistance. This would be better than going to the 3.42's. As Camstyn said, with 3.42's the truck probably couldn't pull itself out of it's own way until you got going on the highway. I think that any benefits gained by going to the 3.42's would be negated by the decrease in town-driving mileage. Case in point, my brother's 99 1500 5.3 gasser picked up 2 mpg when he swapped up from 3.73's to 4.10's.....go figure.


JP

Well assuming I stuck with 4:10's and got 255/85/16's any idea of how it would drive, what rpm it would run at 65, and what mpg difference there would be?

I occasionally tow, but usually in or around town with mid to small loads (occasionally something heavy). What I usually do is do a 750 mile route each weekend with 3000-4000 lbs in the bed for half the trip doing 65 mph.http://www.dieselplace.com/forum/smileys/HiHi.gif

What size tires came stock on your truck, 245's? If so, going to a 255/85 series should make about an 8% difference in your speedometer. Whatever your RPM is at 60mph will be your RPM at 65mph if I've got the % right. It should be very close.

Camstyn, your math checks. I got 7.85% (not including any sidewall flex).http://www.dieselplace.com/forum/smileys/Big Smile.gif What's wrong with the 3.73s? Just curious. . .I've been pretty happy with the gearing and towing ability so far (although I don't have that much experience with it). Gets pretty good mileage too.


Dennis

Camstyn, your math checks. I got 7.85% (not including any sidewall flex).http://www.dieselplace.com/forum/smileys/Big Smile.gif What's wrong with the 3.73s? Just curious. . .I've been pretty happy with the gearing and towing ability so far (although I don't have that much experience with it). Gets pretty good mileage too.


Dennis





He's got the old powerhouse 6.5 and u could actually get different gears in them.

Don't confuse me with the facts, Dmax Tim. http://www.dieselplace.com/forum/smileys/Big Smile.gif I should probably spend just a split second more reading these posts. Seems like I'm always in a hurry. . .

I run 235/85R16's in winter and have been running 265/75r16 this summer.

It would be nice to change tires instead of gears seeing as I havent done a 4*4 before.http://www.dieselplace.com/forum/smileys/Embarrased.gif

ASk and you shall receive:


Tire Sz Tire Hght trans-gear MPH RPMs(3.73/4.10)
245/75 30.7 .70 65 1859/2044
265/75 31.9 .70 65 1789/1967
285/75 33.1 .70 65 1725/1896
255/85 33.3 .70 65 1714/1884


Apparently the 255/85 is only 2/10 of an inch taller than the 285's, but the 255's will fit safely on the stock rims. Hope this helps.http://www.dieselplace.com/forum/smileys/Geek.gif


JP

ASk and you shall receive:


Tire Sz Tire Hght trans-gear MPH RPMs(3.73/4.10)
245/75 30.7 .70 65 1859/2044
265/75 31.9 .70 65 1789/1967
285/75 33.1 .70 65 1725/1896
255/85 33.3 .70 65 1714/1884


Apparently the 255/85 is only 2/10 of an inch taller than the 285's, but the 255's will fit safely on the stock rims. Hope this helps.http://www.dieselplace.com/forum/smileys/Geek.gif


JP





What about 235/85's just out of curiosity. Unfortunately it doesn't look like they offer the 255/85's in my favorite winter studded tires. I guess I will have to consider summer tires only.