I have a '03 Ram 1500 4x4 and can't quite afford to give it a lift but would like to put on larger tires and get those crappy Goodyear Wranglers off the truck. Does anyone know what the biggest tire size I can put on the 17" stock rims. I have read 305 70R17 but need to know for sure. Sticker on the inside of the door says 245 70R17 but I bought the truck new with 275 70R17 on it. Any help would be great.

 

I fit 33*12.50 on mine.

 

A 305/70R17 is about 33.8 X 12

to figure out a metric tire into inches:

1. Take the first number divided by 25.4 This is width in inches (305 / 25.4 = 12.00787) This is 12"
2. Now take that number multiplied by the aspect ratio as a percent (12.00787 x 70% = 8.4055) This is the amount of sidewall from wheel to ground
3. Now take the number from step 2, and multiply by 2, since you have sidewall on each side of your wheel (8.4055 x 2 = 16.811)
4. Take the number from step 3, and add it to your wheel diameter (16.811 + 17 = 33.811) This is the overall diameter of your tire

 

You fit a 33/12.50 with no other modifications?

 

Thanks for the help, but I am not quite sure what all that means.

First of all should I be driving my truck with 275/70R17 when the sticker on the door states 245/70R17?

Second, I have read a bit about getting larger tires and it states that I shouldn't go with more than a 3% increase. If that is true and my truck states 245/70R17 then the 275/70R17 are already over the 3% rule.

So what am I missing?

 

The standard tire was the 245/70R17, the 265/70R17 with cast wheels was a $400.00 option and came with a 3.55 ratio. Thr 275/70R17 was part of an off-road package and 20 inchers could be had for about a grand and required a higher rear end ratio. Drivability will be the limiting factor (loss of power and mpg) unless you make a gear change. With a completely stock truck, some were able to fit the 305s and some have experienced some rubbing at the limits.

 

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