1971 Chevy Suburban Redux

A chronicle of the rebuilding and rebirth of an American classic &mdash the
1971 3/4 ton Chevy Suburban.

February 14 2011

Tall Skinny Tires: 255/85r16 or 255/75r17

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The tires that the Suburban rolled home on were 315/75r16 all terrain tires. That’s big… too big for my blood. I’m not really an off-roader, so a 35″ x 12.5″ tire, for my tastes, just looks silly. To each their own, and if you’re driving over sand-dunes or endlessly deep mud pits, then the bigger the better — but that’s not for me. I’m building this classic Chevy Suburban to be an honest-to-goodness sport utility vehicle: I want to be able to get along on jeep trails (actual double-track trails, not creekbeds), but cruising down the highway is even more important, because there’s a lot of highway between St. Louis and Yellowstone.

Most guys that upgrade their stock tires to a larger size seem to like beefy, wide tires. Tall, skinny tires have more of a small cult following. It seems the consensus among skinny tire proponents is that the 255/85r16 is the ideal tire size. That’s a true 33″ tire, at only 10″ wide. From a performance perspective, that’s probably really the best road manners (quietest and best fuel economy) and the best off-road characteristics in everything but super deep mud or sand. The problem is… you cannot find any sort of selection on these tires. Most of the choices are mud terrain tires, with maybe 3 or 4 choices, and there’s only one all terrain tire in that size that I’m aware of: the Cooper Discoverer ST. Even then, the ST is more like a hybrid between a mud terrain and an all terrain.

I had actually settled on a tire, and ordered a set from Discount Tire Direct. I decided to go with the BF Goodrich Mud Terrain T/A KM2 in 255/85r16. Everything I read is that they have surprisingly quiet ride, and the treadlife is really good for a mud terrain tire. They’ve got a wickedly aggressive looking tread pattern, which is maybe out of character for me, but they look cool! It all makes no difference though… Discount Tire Direct called back shortly after I placed my order, and they informed me that the BFG Mud Terrain T/A KM2 is on national backorder. Bummer. I check tirerack.com… same story.

The next closest size, and my second choice, was the 255/75r17. With the slightly larger wheel diameter, but lower profile sidewalls, the total height on those is about 32″. So I give up an inch in height vs the 255/85r16, but I keep the 10″ width. There are a ton of all terrain choices in this size, but a 1971 Chevy Suburban is a *big* truck, and I worried that a 32″ tire would feel a little small, especially since they’d be replacing 35″ tires. And with all terrain tires vs mud terrains, would they look like stock highway tires on the bug ‘Burb?

I went ahead and pulled the trigger. A couple days later UPS shows up with four Goodyear Wrangler SilentArmor tires in 255/75r17. That rubber would get wrapped around some good ol’ Cragar Soft 8 black steel wheels in 17″x8″. Here they are mounted up:

255/75r17 Goodyear Wrangler SilentArmor

I actually really like the 75-series sidewall profile on the 17″ wheels – they’re not overly balloon-like, the way a lot of larger tires look on 15″ or 16″ wheels. Here’s a shot of the new tires next to the old 315/75r16 tires:

315/75r16 vs 255/75r17

Clearly these 255/75r17 tires are smaller, but not too small. I’m liking them more and more. Here’s a shot of them lined up next to my daily driver, an F150 with 31×10.5r15 all terrain tires:

It’s hard to see really well against the black truck, but that photo still gives you an idea of the change.

On Sunday I got two of the new wheels/tires bolted up to my cleaned up 14-bolt semi-floater rear axle. I added brake lines to the axle this weekend too, so all it needs prior to bolting it up to the truck is gear oil. Here’s a photo of the axle with the wheels and tires.

I like it. I’m really happy with the size, and the Goodyear Wrangler SilentArmors will hopefully prove to be a nice, quiet all terrain tire, with enough tread to get me through a little slush and slop and gravel once in a while.

More updates to come soon. I made more progress on the truck this weekend, got some interior parts, firmed up on a deal for a diesel engine… but for now, it’s late, and I have work to do. Wish me luck!

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