2022 Colorado ZR2, gas 3.6, crew cab short box. stock it came on the 31 inch Duratracs, i went to 285/70R17 KO2s last year and they fit with nothing but a little rub on the mud flap. now the KO2s are at 6/32 and i am thinking 35s for the next set.
i am not lifting it. the DSSV shocks are the whole reason i bought a ZR2 and i do not want to put spacers on them. so the question is what actually rubs on 35x12.50R17 with the stock wheels, and does it drive like garbage on 3.42 gears with 35s. most of my miles are I-90 and the Beartooth when it is open. the BFG size chart on bfgoodrich.com says a 315/70R17 is 34.4 inches, which is the other thing i am looking at.
suspension shop in Mesa. we have put a full 35 on a handful of gen 2 ZR2s with the DSSVs left alone. on stock wheels it rubs in two places: the front of the inner fender liner at full lock, and the body mount behind the front wheel when the suspension is stuffed. the first one you fix with a heat gun and some trimming. the second one is a cut and you will see it every time you look under there.
a 315/70 on the stock wheel is the one i would do. it clears the body mount on most trucks, you still trim the liner a little, and it does not look like it is wearing its big brother's shoes.
different truck but same family. my 2023 Silverado ZR2 came on 33s and i went to 35s in the spring. mileage went from about 15 to 13.5 with the 6.2, the 10 speed does not care much about the size. in your Colorado with a 3.6 and 3.42s you will feel it on the on ramps and in the passes. Beartooth on 35s with that motor sounds slow.
G
grand_junction_raptor
2021 F-150 Raptor 3.5 HO, stock 35s
PrerunnerGrand Junction, CO23 posts · joined Jun 2025
my gen 3 Raptor came on 35s from the factory and i still think it is the right size for that truck. what i would say from driving one every day is the 35 changes the steering more than the speed. heavier, slower to come back to center, more wander on a crowned road. on a midsize truck with a smaller steering box you will feel that more than i do. the 315 sounds smart.
speedometer math so you know what you are signing up for. the truck is calibrated for the stock tire, which is about 30.6 inches no matter what the marketing called it. the 315 is 34.4, so about 12 percent, and at an indicated 65 you are doing about 73. you have already been running around 7 percent slow on the 285s, by the way. that is a ticket in some places and it also throws off your shift points a little and the ABS math a little. on the GM side some dealers will reprogram the tire size in the body module if the size is on their list, otherwise people use a handheld programmer. do it the week the tires go on, not someday.
went with 315/70R17 KO2s. Discount Tire on King Ave mounted them, i did the liner with a heat gun and a pair of snips in the driveway. a little rub at full lock in reverse going up my driveway, nothing on the road. body mount untouched. had a GM dealer in Billings set the tire size, they could do it, 85 dollars for half an hour. speedo now matches the GPS at 70.
ran up the Beartooth on sunday. glamis was not wrong. it is slower on the switchbacks above Red Lodge and i notice it pulling out to pass. i will live with it. build line updated to 34s, which i realize is not a real size.
one more thing now that it is done. get an alignment with caster checked, not just toe. bigger heavier tire on a ZR2 will show you any caster split as a pull to one side, and the DSSV trucks come from the factory on the low side of the spec. ten minutes on the rack to check and it saves your new tires.
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