finally!

[dieseldoug]

just picked up a 2000 with 78k on in......man, i'll never drive gas again!....i have two questions.....the truck has 245 tires and the door jam says they should be 265's......it turns aroun 2000rpm at 70mph......will putting the right size tire drop the rpm's at highway speed a little.....question2.....it has a boost guage and i can't seem to get more than 11-12 psi of boost.......i read in here about the pipe couplings leaking boost......and mine have the "oily" covering at the joints.....what should the stock boost be? thanks dudes......:giterdone:

[kyrel69]

well unless someone has put someone on the truck or had the computer reprogramed, haveing larger than stock tires means that you will be going faster than what the spedo says. (if the are taller)

you have 265x??
and stock is 245x???

you can put a wider tires on with a lower % of and still have the same tire height just some fyi

[dieseldoug]

it currently has 245's but the door jam says they should be 265's.......

[kyrel69]

Originally Posted by dieseldoug

it currently has 245's but the door jam says they should be 265's.......

ok then you may be going slower.

But they are 245x??? what is that 2nd # (245 x 70 x 16 exp)
and they should be 265 x what ??? there is a 2nd # and that is the % of the width and that tell you how tall the tire is.

So you couls have the same height tire and just differen width.

I put 285's on mine. Theyre like a 33" tire. 245 is way to small.:giterdone:

[Lone Ranger]

Hello DieselDoug, from Australia....

Check with your Insurance Company to be sure, but usually it is considered illegal to go smaller than the minimum on the door tag. 245's are Chevy Suburban city sized tyres... It could mean that your insurance could not cover you in some circumstances.

The door tag is the MINIMUM size, larger is OK, but not smaller. It might not pass a Vehicle Inspection in some States for the same reasons.

Regards, Ranger

[super_stroke]

Originally Posted by Stroketechintraining

I put 285's on mine. Theyre like a 33" tire. 245 is way to small.:giterdone:

305's are 33 and 315's are 35. not exact but within an 1/2 inch or so.

[LTJDS]

I have 20x10"s and street radials 305/50R/20's (Cooper ZEON XST's)This is the largest combination you can put on a 99-03 F350 SRW 2x2. Without modifying the factory ride height.
I use to own a 99 F250 4X4 w/ a 5.4L gasser . ,and 305's are, when off the rim, close to 33's and 315"s are close to 35's as mentioned previously.
You should drive at minimum with the correct tire rated for your truck , so you can use your truck to it's design potential.

Go to your local tire shop or check "Tire Rack" on Google and you will rec'v a full tutorial on tire size.

www.tirerack.com
Recomended 2 ALL , I have never even bought from them, BUT they have alot of information about tire size, load, speed and weight ratings. A must check out 4 All.
GOOD LUCK

[lilredpowerstroke]

Originally Posted by dieseldoug

just picked up a 2000 with 78k on in......man, i'll never drive gas again!....i have two questions.....the truck has 245 tires and the door jam says they should be 265's......it turns aroun 2000rpm at 70mph......will putting the right size tire drop the rpm's at highway speed a little.....question2.....it has a boost guage and i can't seem to get more than 11-12 psi of boost.......i read in here about the pipe couplings leaking boost......and mine have the "oily" covering at the joints.....what should the stock boost be? thanks dudes......:giterdone:

To answer the first question if you put 265's on it will still read 70 at 2000 rpms . You will have to go to a larger tire (then have your speedo reprogrammed for that tire size) in order to get lower revs. It really wont change it that much though. And your second question is that is really low. Stock it should make at least 18lbs I think. I dont know for sure its been so long since mine was stock. My boost gauge is where the air intake heater used to be, that way I didnt have to mess with the MAP line.