I'd been running 295's that were pretty worn down, but I had just finished upgrading the tranny and adding a comp box. Loved the added power. Now I knew that adding bigger skins would have some negative effect on the power mods..... but man - my truck felt like a rocket before (for a guy that had run stock for a while) and now feels a lot slower. I'm just really amazed how much the bigger tires slow ya' down. I'm sure the 3.55's dont help at all. Hopefully a set of mach 4's and bigger turbo will help out?

 

Yup, 315's are a great way to slow the truck down - especially with 3.55's......also puts the truck out of it's most efficient cruising rpm....and along with much higher rolling resistance, kills mileage......the ideal solution is a gear swap to put the motor back in it's proper range and to put more torque to the ground.......adding more engine power will make the truck quicker but won't solve any of the other problems that a gear swap can compensate for.

 

Hmmmm...

Mine is a 6 speed with 3.55s, with just some mild mods and I honestly could not tell the difference between the 315s and 265s.

If anything I like the 315s better because they give me more speed in each gear.

Also, keep in mind you speedo is off if your going off that for judgement.

I honestly am getting the same mileage as before. Was at 18.2 last time I filled up with the 265s. I'm at 18.0 with the 315s after 600 miles. Taking into effect the odometer is off, I'm actually getting better mileage.

 

I dont like anything over 285s for

3.54 gearing.... 70 MPH at 2000 RPMS, and not much rolling resistance cannot be beat...

Tx

 

i am at 80 mph at 2000 rpm, 285's and 3.55's in the rear

 

3.55s and 315s here, I didn't notice much of a difference either. I'm at 1800 rpm at 70 mph. If I swapped 4.10s in, my rpms would be high on the freeway.

 

315's made my truck a pig with the funbox off... Figure I may have lost 1-2 MPG over the 285's

 

285 are fine if you don,t tow! the same for 315,s for me I just hit the underdrive then haul away!!

 

265's and 2200 rpm's at 70. need taller tires someday. thinking 295's?

 

Highway driving here is 80-85 MPH, so, 2000 RPM @ 80 MPH(with 315s) = good fuel economy

 

I haven't had any problems with my switch from 265's to 315's. Truck rides smoother and I get 18 mpg in town and 20 mpg highway. me likey. I don't tow much so no big deal for me, but I would not recommend 315's if you plan on towing alot. maybe 295's or 305's. I think they are the same height just 305's wider. jmho

 

FWIW, with 315's, 3.55's and an auto, you are not going 70 mph at 1800 rpm! You will be going faster.....I take it you didn't have the revs per mile reset in the PCM for the larger tire?

 

295's

are taller and narrower than 305's, but about the same height as a 315 tire


Tx

 

No I haven't had anything adjusted for the tire size yet. Once I get rid of my Nittos I was going to get my truck adjusted for some BFGs. So what would my rpm/mph be if it were adjusted?

 

Ok, here is my calculations for you....assuming your 315's are about 34.9" tall.....

Revs per mile is 578.2

With an auto, 315's and 3.55's, actual rpm should be 1,416 rpm @ 60 mph and 1,614 rpm @ 70 mph.