excuse my squirrely ignorance

[beallendall]

so I am thinking bout putting some new shoes my truck. problem is I am a complete noob at this. I have the offroad pkg. which I know means I have the 17" x 7.5" aluminum wheels. My question is can I put 18" wheels on without worrying about rubbing without putting a lift on. It looks like an inch won't matter all that much, I know though the size tire I also get matters. But I like the size of the stock tires. So I doubt I would change the size of the new tires that much. Any suggestions from the 'pros' out there? I am not looking to lift my truck, just wanna add some individuality alittle at a time right now.

btw here's how I got the title of the post: http://www.illwillpress.com/sml.html

[beallendall]

oh and can anyone break down what the tire description means? for example the stock tires I have are: P285/70R17. What does that mean?

[goathead]

here you go.

http://www.cjtire.com/pdfs/Tire%20Identification.pdf

steve

[IMADOGMAN]

Originally Posted by beallendall

oh and can anyone break down what the tire description means? for example the stock tires I have are: P285/70R17. What does that mean?

P means metric radial

285 is the width of the tire in millimeters

70 = 70% The tire sidewall height is 70% of the width 285 x 70% = 199.5 mm

R = Radial

17 = rim diameter.



When you change to an 18 inch rim, you don't necessarily change the overall diameter of the tire. The 18 inch stock tires are P265/70/18 which is 20 mm narrower, which makes the sidewall height 185.5 mm (28mm less overall sidewall height than the 17 inch stock tire) The stock 17" and 18" tires are very close to each other in diameter. Doing the math, the 17" tire should be 32.7 inches in diameter, and the 18" should be 32.6 inches in diameter.

285 x 70% = 199.5 x 2 = 399 /25.4 = 15.7" + 17" = 32.7" diameter (17" assy)

265 x 70% = 188.5 x 2 = 377 /25.4 = 14.8" + 18" = 32.8" diameter (18" assy)

[Cajunguy]

OK then, here's a simple question:

On the off-road stock rims, (17" x 7.5"), can I run a tire size OTHER than 285/70/R17's, to give me a larger OD?? And if so, what size can I use without changing the stock rims??

Thanks.

[IMADOGMAN]

You can certainly run a bigger tire on the 17" rims. I suppose any size that doesn't rub anywhere on the truck would be okay, but if you look at the proximity of the front tire to the body, you can see that it couldn't be much larger without hitting...unless you lift the front. Be aware that changing to a larger diameter will throw off your speedometer and will change your overall gearing.
Others here may have gone to bigger tires, and can tell you which ones will fit without interference problems.

[beallendall]

Thanks Goathead and Imadogman. 3 months reading this board and I know more about trucks than I ever did. High School automotive classes should just read this forum for all they need to know. LOL. Thanks again guys.

[DallasTitan]

This helped me a lot:

http://www.miata.net/garage/tirecalc.html

http://www.discounttiredirect.com/di...foTireMath.jsp