Engine/Transmission (1998.5 - 2002) Auto/3.54's/315's... Problem?

[sparks57]

I'm thinking about throwing some leveling springs on my new truck (SJ D25's) and I was thinking about then puting 315/75 tires on.



I was warned that the auto/3. 54/315 combo was a bad mix.



Anybody here have an opinion?

 

[Cooker]

If you tow heavy I would not do it as it will increase your spool up time significantly.

 

[MUDDY]

i wldnt go more than a 285,,,,,esp if u gwine tow

 

[Snow man]

auto uses 2. 45 to 1 first gear, bad mix,and heavy towing ,the 315s have too much sidewall anyway leading to a wallowing feeling. i love them with my 4. 10 auto though. there a perfect al around tire.

 

[MDale]

I have 285's right now and was thinking of going to 315's, what kind of drop in mpg will I see?

 

[sparks57]

How about 305's? I just don't like the look of the stock 265's... too small looking IMO.

 

[MUDDY]

285s look ok. also more affordable. also good selection. u will like em bttr in the long run unless ya be off road 90 % of time

 

[edgrim]

I went with 315/70R17 I had 3. 54 gears but didn't care for the low end response (what low end response!) truck was real doggy. Someone here pointed out that 315/70R17 or 315/75R16 and 4. 10 gears give you real world 3. 78 final ratio which is a great combo! Anyway it's true and I love the way the truck goes now with the minor bombing I've done. I also put on the D25's but my rear end looked too low, it wasn't but the optical illusion drove me crazy. I have some taller lift blocks I bombed to push up the rear. They're for sell, if your interested pm me.

 

[cwarner]

I've got 3:54's and 315 BF Goodrich's (don't remember if they are 75s or 70s) on the factory 16 rims and have no problems. I usually only tow around 7000lbs but on the occation that I've towed 11,000 I had to keep the speed up (70-75) or the truck was out of the power band.

You can fit the 315's on the stock set up if you don't mind a little rubbing , I only notice it if I'm manuevering in a tight parking lot or backing a trailer up in a tight area.

I didn't want the leveling kit because when towing the truck probably wouldn't be level.

 

[Patriot Diesel]

I have been running 315's with 3. 54 gears on my truck for the last two years or so. Before that I had 305's. The 315's do, IMHO, look much better.



I will say that you definately lose a little bottom end response. OD is not really useable below 65 mph, RPM's are just way too low. I think 70 MPH in OD is approximately 1700 RPM's.



Highway crusing is fantastic... 75 MPH is somewhere around 1800-1900 RPM's.



Unless I am at 65 MPH or above I leave OD locked out.



I have towed abut 5000 pounds with 315's with no problem at all. I used to have a 33' 5th wheel that weighed in somewhere around 9000 pounds. I towed it just fine with 305's.



I wish my truck had 4. 10's...



3. 54's and 315's are liveable, just not ideal, IMHO...

 

[sparks57]

Shoot... too bad this truck doesn't have 4. 10's. I'm sure there's someone out there that wants to trade 3. 54's to 4. 10's.



I'm not too concerned about sidewall flex, but I will be using 17" rims, so no biggy.



Thanks a lot guys.



BTW: you can't get 10 ply 285's, that's why I don't want to get them.

 

[Cooker]

Originally posted by CB_Parker

BTW: you can't get 10 ply 285's, that's why I don't want to get them.

I was not aware of any 10 ply 315's?

 

[Chipstien]

What Cooker said... ... . spill the beans.

 

[damon]

with 4. 10's I saw no difference at all in mileage when I installed the 315's. Of course I only get 15-16 so it never was great anyway.

 

[klaybus]

I'm thinking about throwing some leveling springs on my new truck (SJ D25's) and I was thinking about then puting 315/75 tires on.



I was warned that the auto/3. 54/315 combo was a bad mix.



Anybody here have an opinion?

Chris,

I'm running 285's with 3. 54s & towing is kinda a bummer! My truck with an EZ pulls it fine, but with the taller tires it throws the gear ratio even taller (stock tires were 245's) so using OD doesn't work well. Running down the freeway empty however I love the 3. 5s... I commute 60-80 miles per day & love them then.

Good luck on your decision.



Clay

 

[IWeiny]

Why not 3.73?

I still don't understand why something between 3. 54 and 4. 10 was offered.



Oh well.

 

[Chipstien]

I still don't understand why something between 3. 54 and 4. 10 was offered.



Oh well.

You mean "wasn't offered"