WILL 35's or 37's: A) ruin an auto transmission? B)Void warranty?

[jasonps]

I have heard, from a FORD guy, that putting 35-37inch, or larger tires will adversely affect the tranny (auto)shifting points, leading to a shorter life, and void the warranty in case this is to happen. i have even heard that a dodge guy ruined his tranny and also his electronics due to putting bigger wheel/tire combos on. warranty did not apply, so he was out some major $. So i am asking anyone out there with some knowledge or experience to post a definite answer. i have 33's rightnow and am wanting to go to 35's possibly 37's with a regear in the future, with the TC lift. am i to expect a severely shorter tranny life?with no warranty....?...... i do tow a trailer on a reg. basis.

thanks for replying! this site helps a lot......

[Y2kn1Tun]

Yes, switching to larger tires will put more stress on your tranny, IF you stick with the stock gears. If you regear to 4.56 or 4.88's then that should take most of the stress off the tranny, and extend its life.
lata Wes

[Agent WD-40]

It should not be a problem if you regear.

[jasonps]

what about those programmers that they have for chevy and fords? is there one for Toyota? and if so do they help?
what are the stock gears in the Tundra? i have a 3:90...is that standard equipment?
the 4:56 rearend with 37's would do what to gas mileage? about the same as stock or drastically lower gas mileage, i know it would hurt top speed but i would guess that it would have a hellacious launch, so that would bring me to other questions, like would the driveshaft hold up, ......READ):...a S/C ed, lifted, 37 inch tire smoker...........cool

[KLS]

Here's an easy chart to follow for tire diameter and rear end gear ratio. http://www.4lo.com/geartable.html

Original tires on our trucks are about 30.6" outside diameter, and the original differential ratio is 3.91, so just follow the green boxes.

No, you don't get more power with a lower gear ratio (4.88) AND 37" tires---you'd have the same power as shown by the green boxes on the chart. What you gain with the gear ratio is lost with the big tires.

Don't believe their suggestion of better gas mileage when you're in the zone of the yellow boxes. On our trucks, the combination of the overdrive ratio (0.7:1), the differential ratio, and the OE tire diameter is about optimum for gas mileage. A higher effective ratio (lower number differential gears or bigger tires) usually means that the transmission is spending more time in overdrive with the torque converter unlocked, or in 3rd, so gas mileage suffers.

Ken