Tire size question

[jeffd]

2013 Silverado 1500 LT Ext Cab 4x4 Z71.

Bilstein 5100 F&R, set to 1" in front.

Stock tires 265/65-18

 

Can I run 275's or maybe even 285's?

With either would the speedo need re-calibrating?

[Corben]

Yes you can run 285's without worry of the spedometer being off. The 2-- numbers are width of the tire, the 2 digit number in the middle is aspect ratio. For example, if you get 285/65/18's, then the tires will be wider than stock, but same height.

[Big Whiskey]

2013 Silverado 1500 LT Ext Cab 4x4 Z71.

Bilstein 5100 F&R, set to 1" in front.

Stock tires 265/65-18

 

Can I run 275's or maybe even 285's?

With either would the speedo need re-calibrating?

With only 1" of lift in the front, it may be tough to fit 275/70/18 or 285/65/18. Those are two of the most popular sizes for a leveling kit. However, you should be able to clear a 265/70/18 or 275/65/18. I ran 275/65's on my last truck, and they worked well. There are pics in my gallery if you're interested. Your speedometer will be off by the percentage of increase from stock tire diameter to your new tire diameter. Most people just compare it with GPS, and drive accordingly.

 

Yes you can run 285's without worry of the spedometer being off. The 2-- numbers are width of the tire, the 2 digit number in the middle is aspect ratio. For example, if you get 285/65/18's, then the tires will be wider than stock, but same height.

That's not true. You're right about the first number being the width in millimeters, and the second number being the aspect ratio...but I think you're a bit confused about how the aspect ratio effects the overall diameter. Lets take the comparison of a 265/65 vs a 285/65...the 265 is 265mm wide, and the sidewall is 65% (because the aspect ratio is 65) of the width (which comes to 172.25mm). To find the overall diameter of the tire, you double the sidewall mm and convert that to inches (172.25 x 2 = 344.5mm...which is 13.56 inches), then add that to the rim diameter (13.56 + 18) and you end up with a 31.56" tire. Now the 285/65....285mm x .65 = 185.25, then 185.25 x 2 = 370.5mm, which is 14.58 inches. Then, 14.58 + 18 equals a 32.58" tall tire.

 

Another example would be how there's only a tenth of an inch difference in the diameter of a 275/70/18 and a 325/60/18. It's tricky stuff!