40’s are the new 37’s

Only an off-road enthusiast would understand the saying, "40s are the new 37s." Since you readJp magazine, we figure you do know. It refers to tire diameter for Jeeps. No we don't talk about those silly P-metric 245-blah-blah sizes on a Prius. We Jeepers talk in a secret code of tire sizing that is still in inches of diameter, and any sensible person knows that bigger is indeed better. But then again, how can you fit a 40-inch tall tire on a stock Jeep? For the most part, you can't. At least not so that it can drive.

But through the years we've seen the industry ramp up from 29-inch tall stockers to that massive 31x10.50-15 Armstrong Norseman Tredloc tire. And then came the all-hallowed 33. A standard of the industry for years, it was the go-to tire size—the new 31 as it were. Only the big mud trucks ran huge tires, and by that we mean 44-inch Ground Hawgs and Gumbo Monster Mudders, and they were on 15-inch rims. Those were some huge sidewalls with this little donut of a rim inside.

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Then come along the '90s, and crazy Jeepers started using 35-inch tires on Jeeps. It was heresy at the time to run such a big tire, but sure enough, with spring-over conversions and body mods the 35-inch tall tire became the new 33, and some even came in a 16-inch rim size! By then, stock Wrangler Rubicons were fit from the factory with 32s on a 16-inchrim, and the end wasn't in sight. By the time the JK Wrangler was introduced, 35s were the go-to size, and the 37 burst on the scene with 17- and 18-inch rims.

Where would it stop? Enter more suspension offerings and wheelwell modifications from the aftermarket, and indeed, the 37 was the new 35 on every modded JK around. Recently, the scene has changed yet again for the mainstream Jeep modifier, and those 40s that crazy Jeepers ran are now the new 37. With a handful of mainstream manufacturers making a 40-inch tire, the options seem endless for fitting the JK, and maybe the new JL Wrangler. But where will it end? 42s? Back to the old 44s? While I doubt we will ever see 48-inch DOTs running down the road, even the ATV market is up to a 33-inch tire, back where we started years ago.