Quote:
Originally Posted by 88Racing
Calculations I got with out "squish".
Stock
275/55R20-2546mm
Spare
275/65R18-2559mm
Difference tells me spare has 1/2" more tire in circumfrance. The post I did earlier this thread about being about equal is not true. The spare should only be ran as a spare(temporary) unless you change all 4 wheels to that size or get a 20" spare.
Lars
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Interesting, Lars. TG150 (Tony) and I have had several back and forth's by PM this morning. For everyone's information, he loaded Level 2 without doing anything with "Custom Options" and his Gryphon speed exactly matches the speed shown on his GPS (and, of course, the truck's dashboard speedo reads 1-2 mph faster). I suggested he leave well enough alone and not mess with the tire size.
Lars, I don't think he ever said what his stock tires were, but the new tires are different than yours. So, it's quite possible they have the same rolling circumference.
I'd be quite cautious in any case if the stock spare were put on either of your trucks. I'd sure keep the speed below 55 (like when using a space saver spare) and try to get the road tire back on as soon as possible.
- Jack