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March 2011 Inbox: Letters to the Editor

Ford F150 Raptor
Rick Péwé
| Four Wheeler Network Content Director
Posted March 1, 2011

What is a Prerunner?

What is a Prerunner?
I salute the Potentate of Power and request his infinite wisdom.

I've been grinding gears off-road my whole life, but I don't get the word prerunner. It's used often in your magazine, your great magazine, to describe everything but a Toyota truck. You even called the Raptor a "factory-built prerunner"! What gives, O great one?

I run 285/70R17s on my Dodge. What's the "285"? I know it is tire height, but 285 of what? Is it just foolishness like the old F70 or D78 designations or what? What gives, my leader? Don't use "metric equivalent" or "arbitrary" in your answer, please.

My tires have gone up from 25 to 45 bucks this year. Are the tire company guys doing us like the oil companies? Is it the Feds? They sell 100 million tires a year and that's some serious revenue, Daddy-O! What gives, boss?

Free my tortured soul from ignorance.

A prerunner is a style of truck used to prerun a race, common in off-road desert racing. The equipment used to modify the truck is intended to allow the vehicle to go faster over extreme bumps and terrain while providing a safe and controlled ride. It isn't supposed to be a flat-out desert racer, but at least close.

On your tires, the sidewall size designation is indeed the metric equivalent of the old F70 style of markings, but hardly arbitrary. In fact, it's quite sensible. The "285" is called the section width as measured from sidewall to sidewall, in millimeters. The "70" is the aspect ratio, which is a percentage of the section width to the height of the sidewall. So your tire's sidewall is 70 percent of 285 mm, or 199.5 mm. The "R" indicates a radial tire; a bias tire might be marked with a "B," a dash, or a space. The "17" is the rim size in, yes, inches. So your tire's total height is 32.75 inches because 199.5 mm multiplied by 2 is about 15.75 inches, and you add that to a 17-inch rim. Go to and check out the whole story.

Lift Laws Feedback
Hey guys, I was just reading your October issue and was reading up on the New Jersey lift laws. I just took my newly acquired '90 Chevy Blazer on a 6-inch lift with 35s through the stability testing. The Asbury Park location where you photographed the tilt wall is where I had my truck on the 19th of August. I have a listing of applicable rules and regulations provided by NJDMV on oversized vehicles. You hit the nail on the head but missed a few things.

New Jersey has moved away from safety inspections, only doing emissions testing now, so it is the owner's responsibility to ensure safety. Overall, the testing of the stability takes 35-45 minutes to load the truck onto the scales then balance it with the driver-side wheels up on the comedy act of a bump and the passenger-side wheels on the scales. After that, the truck is measured on the front and rear bumpers and in the inner doorframe on the driver side, the wheel height and width are checked, and everything is crunched in a computer.

Now the real adventure is the mud flaps. They will penalize you and fail you if they do not come fully down to the bottom of the rim. I found out the hard way, as I was 1/8 inch short. In all, though, you hit it dead-on, like I said. There were just a few things you missed. Keep up the great work, and keep the muddy action rolling.
Bayville, NJ

Man, we need to move to Bolivia to get away from red tape. I hear you get more for your money there. Thanks for the N.J. update!

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