I was wondering how much of an RPM drop I would get going from 265 tires to 315? My truck is an 04 auto with 373 gears. Also any idea if this is going to cause long term damage to the auto transmission? Driving is mostly highway pulling a 6000 pound trailer.

 

12.8% <--- apprently that message alone is to short to post.

 

(Original OD / current OD ) * RPM

so if you curent tires were 30" and your new ones were 32" at the speed you would be at 2,812 RPM, not 3,000.

I up sized my tires to 32" od and dropped my RPM by about 200 RPM at 70 MPH. I had my speedo re-calibrated.

I am not ware of any long erm effects but I does put more strain on the engine and drive train, especially at lower speeds.

 

im sorry that was 12.8% on a 2nd gen over orignal tire size of... 265x70x16 or something

 

It would be about a 9% difference or almost 200 RPMs at 2000.

 

at 70 mph i am running about1780 rpms

 

My rpms @ speed with 3.73 gear

1800 = 70mph
1900 = 74mph
2000 = 78mph

Definately improves highway driving in my opinion.

 

9% sounds about right. I had 245s on my truck stock, and when I put the 315s on it changed my speedo 13% according to my GPS.

 

I was thinking about the same tire upgrade, but I am a little concerned about pulling a 10K 5er....I don't want to smoke the tranny....any ideas??

 

ZOG
I would not recommend running the bigger tires with a 5er. I am thinking you would find the truck sluggish and you would have more heat in the trans. due to you taking more time to get up to speed before TC lock up.

I have a 2001 that used to be the primary tow truck for our 5er. I run 315 BFG A/T but when I pulled the 5er I put the stock 265 tires on the truck. My main reason was for keeping the 5er as level as posible. I have enough HP/Torq to pull with the bigger tires if I wanted to

Hope this helps
See Ya
Chris

 

I just bought a 2005 2500 QC 4X4 with the CTD and a 6-speed maual tranny. Can I put 315's on it without a lift and will they fit on the stock 17x8 rims?

 

315's are fine without lifting. i pull a 10k gooseneck and it is fine. in 4th gear you really gotta be cruisin to keep the rpms up in the good area. got my edge and it is even better

 

Here are 315s on a stock truck. I get minimal rubbing.