Bigger tires, Gear Ratio, Trans shift points

[jbush]

I have a 2001 2500 QC 4X4 with 3. 55 gears and 265/75/16 tires. I pull a 30' RV some and car trailer. I would like to go to a bigger tire (285 or 295/75/16) and need to know if I need to make any gear or programing changes, basicly what do I need to look at. Any recomendation? I would like to keep from tearing up the transmission. Any reference material or book names would help.



Thanks,

 

[Matt400]

Auto or stick?

 

[jbush]

Auto trans

 

[Matt400]

Probably would be ok as long as you don't tow in OD. I use OD but have 3. 73's.



Maybe the taller 295 if you keep OD off would work well with those tall gears.

 

[Snow man]

It will work,but your not going to be happy with the towing power in OD unless your towing on flats only and keep your speed at 75+mph so you have 1900 showing on the tach. You'd be much better off towing with OD off,let it rev a little,the trans will live much longer,the only thing i t might hurt is fuel economy. The 4. 10 would be much better for what your doing,but i dont feel the gear swap is worth it unless the majority of your miles are towing. It just wouldnt pay off. You dont want to tow heavy below 1750RPM,keep it over that,for the transmission,and the truck shouldnt suffer from the taller tires

 

[jbush]

Thanks for the info, checking all my options. If I go for the bigger tires, what do I need to get to monitor the trans and keep things in check?

 

[Matt400]

Originally posted by jbush

what do I need to get to monitor the trans and keep things in check?

I installed a SPA Digital Temp/Temp Gauge that serves as an EGT/Trans temp gauge.



What I like about this gauge is that you can select what temp you want the warning lamp to go off at to get your attention plus it will recall the highest temps attained till you clear them with the red button.



Looks like this:

#ad




In all my research I found up to 195 deg measured in the pan is a max safe temp operating value. 200-220 you should investigate options for correction such as a larger cooler. 225 and its time to pull over and idle in neutral till she cools down.



Now if you mount your temp sensor in the trans output line then 270 is pull over time but I couldn't tell you what normal temps measured there should be.



For towing I change trans fluid & filter every 15K.