Tires, Yet Again!

[MuddFlapp]

OK,here's what's up, I'm getting ready to buy new skins for my truck. Curently I have Dunlap 235\75\16s on it. Now I'm going to Michlin ltx's in a 245\75\16. So, My question concerns my spare that is the stock 215\75\16. Will my new tires be so much taller that I need to buy a new spare? What does each set of numbers indicate in a tire size? And, isn't there a web site that has all of this info?
E-mail is fine if you want to, all help geatly appreciated.

Thanks, GE


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Gene Earl, White '97' 3500 Laramie SLT, Ext Cab, LB, 5 SPEED, 4. 10 Limited Slip, 4X4. Isspro Boost and Pyro, (pre-turbo), SW Fuel pressure, in a 3 guage A-Pillar mount. No muffler. K&N filter. (it's a start).

 

[Cooker]

TO answer a few of your questions.

The fist number (245) is the width of the tire in millimieters.
The second number is the aspect ratio of side wall height compared to the first number. That what it is but I cannot calculate it properly.

As far as your spare. On the front it should be ok, but NEVER put the smaller spare on the back. The reason is you have an LS in the rear end and the smaller tire will trick the LS into engaging. This will severly shorthen the life of the LS unit, and potentially overheat the rear end and damage other components.

 

[Ranger Dick]

Muddflap, like cooker says, the 245 is the maximum sectional width of the tire at the widest point, and to convert metric, you divide millemeters by 25. 4 so 245/25. 4 equals 9. 65 inches. the second number is the aspect ratio, the relation of side wall height to sectional width, the is expressed as percent, so 245/75 means the side wall is 75% of the sectional width or 7. 23 inches. To calculate total tire diameter, you then multiply the section height 7. 23 x 2 +16, the rim diameter. which comes out to be a tire 30. 47 inches tall. hope this helps.

 

[RonaldLarson]

Good advice, so far. A good tire shop can give you the exact diameter of your old tire, and the new ones you are considering. Just ask to see the specs. If you aren't going to rotate using the spare, buya used tire of the proper diameter for the spare.
Ron

 

[Forrest]

http://www.thisoffice.com/calc_tire3.html
http://pw1.netcom.com/~sgalaba/tiresize.htm
http://www.tirerack.com/tires/tiretech/truksize.htm
http://www.tirerack.com/tires/tiretech/truksize.htm


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[willyslover]

1. Not a good idea to have two tire sizes on an axel [any axel] and must not be done on a dually's axel 2. the tire size for a dually from your vintage was 215/85/16 not 75 as shown . . I agree with ol ron buy a good used one of the same size and tread pattern/brand for the spare if your not going to rotate with the spare. And it is not a good idea to mix tread patterns on a 4x4 as it can cause the front and rear to swap ends in a panic stop [in wet or snow conditions can be even more sensitive]
OH. . BEST ADVICE. be leary of tire shops info as they [most] will tell you what you want to hear to make a sale. .

[This message has been edited by willyslover (edited 03-25-2001). ]

 

[Pete Peterson]

Dick , like the rest have said, always match up your tires including the spare. Your truck came from the factory with 215-85-16 E range. If you were to go to a 235-85-16 in a Michelin A/T you would fill more of the fender well and the ride would be most exellent... ... Pete

 

[MuddFlapp]

Most excellent gentlemen, once again I am in information overload. Your replies have exceeded my needs. Thanks again to one and all. #ad


GE

 

[Deezal Man]

While we are on the subject,

Those of us running 285's... What do you carry for a spare? Tried fitting a 285 underneath... didn't work so good.

As of now, I'd be forced to mount my factory 245 spare.

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98. 5' Emerald Green 24v 2500 Auto/3. 54 4x4 SB QC 285-75-16's on Alcoa's. Everything but leather. PIAA 1200's, AMSOIL dual filter relocation system, Smittybuilt Stainless Steel Nerfs, Rhino Liner(Junk), AMSOIL air filter.

 

[Fred Swanson]

Still have the new factory 265 spare underneath. Just installed 285's.

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Fred Swanson
Co-Owner
Canyon State Components, LLC
www.canyonstatecomponents.com

'00 QC,SB,4x4,Auto,3. 54 w/LSD,Trailer Package, Tow Package, DTT's VB & TC

 

[MuddFlapp]

Anybody ever try a set of BFG comercial LTs?
They come in a 235/85/16 Load Range E.

 

[willyslover]

MudFlapp. . may I suggest that you look at the XPS Michlens also... they come in both traction and hwy treads. . They have a very tuFFFFFF sidewall comercial rated also. . factory originals I got 20K miles out of them. . the XPS I got 60K out of and I drive the HELLL out of them in the mountains. .

 

[MuddFlapp]

Absolutly, the XPS Traction is what I am now after. I saw a picture of them on the Michlen site, they look like exactly what I need.

[This message has been edited by MuddFlapp (edited 03-29-2001). ]

 

[Matt42]

Do the XPS Traction tires come in LT 245/75R16? The last I heard, they were only available in XPS Rib in that size. An alternate would be XPS Traction in LT 235/80R16. As a side note, I use the XPS Rib on a 3 ton equipment trailer at work. It gets towed into ghastly places. Never a problem with them.

 

[ralphr]

OK I maybe joining this a little late, good info on tire calc using java! dumb question from a dually owner, I thought the 215's were the widest I could use? have 35K on originals, still look pretty good, prehaps another 10k? But now is the time to srat looking for bargins before I absoulutley need new ones. thanx.

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1999 3500 quad cab, auto aero fendor trim and running boards,
bugflector II, K&N filter, Geno's monster tip

 

[willyslover]

Matt . . don't know, call over to Costco and ask. . they can special order what they don't have in stock and save ya a couple $$

Ralph. . yes that is the recomendation . . however the 235's in a super tuff sidewall design will not roll over/flex and will fit and run nicely. . I got 60K on a set with ZERO issues. . also the '01's now carry 235's on a larger offset wheel

 

[ralphr]

willysolver, thanks for the info! I'll be on the lookout for bargins in the 235 size, E rated tire!

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1999 3500 quad cab, auto aero fendor trim and running boards,
bugflector II, K&N filter, Geno's monster tip