Swapped my 35s for 37s and lost a whole gear on the highway

Tbh I thought going up to 37s on my Tacoma would just eat a little more gas, but I lost 5th gear almost entirely on the interstate in Flagstaff last month. The climb up to 7,000 feet had me down to 55 mph in 4th just to keep temp stable, and my speedo is now lying by about 8 percent. I regeared the diffs last weekend from 4.10 to 4.56 and it feels like a different truck, but I wish I'd done the math before dropping $1,200 on tires first. Has anyone else gone up a tire size without regearing right away and just dealt with the doggy passing power for a while?

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bettywilson24d ago

I read a guy on a Tacoma forum say the rule of thumb is one gear lost for every 2 inches of tire you add, and your post pretty much proves that out. The speedo being off 8 percent makes sense too, that is just the bigger tire spinning slower so the computer thinks you are going faster than you are. A lot of people just live with the doggy passing power for a year or two and then regear when they can afford it, but honestly a 4.10 to 4.56 jump on 37s is on the weak side anyway, most folks go 4.88 or 5.29 for that setup. The money hurts either way, tires first or gears first, there is no cheap order to do it in.

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