Originally Posted by Uplink
Just to give you an idea, my 245/40-17 Z2's (listed on Tire Rack as 25lbs) on RPF1 17x8's with no tpms weigh in at 42lbs while my stock wheels/tires/tpms weigh 41.8lbs each.
If you're going 225, definitely don't mount them on the 9's.
As to swapping sizes, looking over the rules I found this:
"7) The following DOT-approved tires and those R-compound tires with a UTQG treadwear
rating over 40: BFG Rival S, Bridgestone RE071-R, Maxxis RC-1 (examples: Kumho V700,
Kumho V720, Michelin Pilot Sport Cup & MPS Cup 2, Nitto NT01, Pirelli PZero Corsa,
Toyo R888, Toyo RA-1, Yokahama A048, etc.) +6"
So you're looking at +6 regardless of which tire compound you select, then the sizing would follow this...
"10) The following tire sizes will be used as the base tire size for each Base Class for all
vehicles regardless of their OEM tire size(s) or their Final Competition Class. All
vehicles in a given base class may use this tire size (or smaller) without a points assessment:
TTB: 265mm, TTC: 255mm, TTD: 245mm, TTE: 235mm, TTF: 215mm,
TTG: 195mm, TTH: 175mm
Tire width points assessed or points credited are determined by the difference between the
width of the largest tire on the vehicle and the assigned base tire size as follows:
Equal to or greater than: 10mm +1, 20mm +4, 30mm +7, 40mm +10, 50mm +13,
60mm +16, 70mm +19, 80mm +22, 90mm +25, 100mm +28, 110mm +31
Equal to or less than: -10mm -1, -20mm -4, -30mm -7, -40mm -10"
Which means you wouldn't have a penalty for running 245 RE's in the wet since that is TTD base size but you should actually recoup 4 points when running the RC1's. Depending on what other mods you have you may want to run the 225 RC1's for point allocation alone but be aware if it's a wet day and you were at max points, you'll be over running 245 RE's when you lose the 4pt credit.
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