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You can't measure the tire height with the weight of the car on it. A BFG 235/60/15 is factory rated at 26.1" tall on a 7" wide wheel. The 275/40/17 as stated above is 25.7" tall on a 9.5" wide wheel. You will see a slight height change based on wheel width but not much. 255/45/17's are also 26.1" tall on 8.5" wheels.

The 255 is the width of the tire, the the 40-45-60 is the percentage of the width that the sidewall is. For example a 255 is the metric measurement in millimeters of the widest part of the tire (section width) There are 25.4mm per inch so divide 255 by 25.4 and you'll get 10.04". Next multi that by .45 which is 4.5" tall sidewalls. now add 17" + 4.5" + 4.5" and you get 26" tall tires.

Now I rounded the numbers and every manufacture differs on the exact width of a 255mm wide tire so you'll see a tenth here and there difference.
 

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Mark,

The 17" tire is a 275/40/17.

Converting the 275 to inches (multiply by .03937) gives you a 10.82675" wide tire. The sidewall is therefore 4.3307 (width X 40%). The final diameter is the rim size (17") + sidewall + sidewall which would equal 25.6614".


As for the 235/60/15 tire.

235mm = 9.25195" wide tire
60% of width = 5.55117"
Rim diameter + sidewall + sidewall = 26.10234" tire diameter.

The 15" tire is taller than the 17" tire because you are only using 40% of tire width on the 17" tire for your sidewall but using 60% of tire width for the sidewall on the 15" tire.

Hope this helps.
 

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Discussion Starter #6
Yes that sounds good , I just wanted to make sure that the size they gave you was when they were mounted on a Rim and aired up . I have the car up in the air right now and I,m trying to figure out my ride height , I,m trying to order my rear QA1 shocks .
Mark .
 
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