American Classic Kimberlite 700 X 40mm Tires: Getting Rolling

American Classic Kimberlite 700 X 40mm Tires: Getting Rolling – by Guitar Ted

American Classic tires have been reviewed here before recently, but we did not get the Kimberlite model. Now that the American Classic line has been updated, we requested a sample of the Kimberlite to review to see if we can feel the differences and to test out this minimalist tread.

A rolled up Kimberlite tire on top of a box on a table with a plant.
The American Classic Kimberlite tires in 700 X 40mm size.

What It Is: The Kimberlite is a tire that American Classic says is meant for pavement and mixed-surface rides. However; here at Riding Gravel’s home, we have found that a minimal amount of tread works fine on deeper, loose gravel. Where we would recommend a more aggressively treaded tire would be in loamy soil, dirt, and rocky roads where steep climbs and sweeping turns are more commonplace. But for a lot of riders, a pavement to gravel to pavement ride is not uncommon. And furthermore; many riders are using these ‘gravel’ bikes as their ‘road’ bike as well. So, a tire that can roll fast on pavement, has the volume for gravel travel, and doesn’t give up on you when the going gets rough is a desirable tire for many of us.

Detail shot of a Kimberlite inner casing.
The interior of the Kimberlite’s casing looks decidedly different than the previous American Classic tires’ casings we tested.

The Kimberlite fits this bill well. It features a slick central strip of rubber flanked by two shallow grooves which border two strips of file-like tread. Then the shoulders have an array of finer, small blocks which have small, low-ish blocks interspersed with smaller blocks lining the outer edges of this tread surface. This promises a fast roll on smoother surfaces.

The casing construction features the new updates said to enhance ride feel and lower the rolling resistance from the previous version of this tire. Here we see a 120TPI casing with American Classic’s Stage 5S Armor protection which American Classic claims is lighter, more cut resistant, and faster than the outgoing technology. The rubber compound used in the Kimberlite is American Classic’s “RubberForce G” which they claim is specifically designed for the gravel tire range. The carbon black used provides “excellent abrasion resistance, high tensile strength, and good tear and cut resistance for off-road adventures” according to the American Classic site.

The Kimberlite comes in 700 X 35mm, 700 X 40mm (tested), 700 X 50mm, and a 650B X 47mm size. All sizes are available in black wall, skin wall, and a new brown wall (tested) color. All variants are tubeless ready with folding beads. The updated tires are available consumer direct from American Classic’s Amazon store for $45.00 USD.

Detail shot of the American Classic branding on the Kimberlite tires.
The American Classic gravel tire range now can be had with this brown sidewall as well as black or tan side walls.

First Impressions: The Kimberlite tires arrived in the same cardboard box retail packaging as the tires we tested last year did. I happen to like the cardboard box packaging as it is easier to store and looks great. It also is recyclable and not plastic, which I think is better for the environment. Nice!

The tire has a different hand feel than previous American Classic tires did. The casing interior is quite different with a grayish toned, finer looking material than the previous tires. The casing feels less thick, and it feels more flexible, not as ‘dead’ feeling in the hand, if that makes any sense. I’ve handled thousands of different tires in 30 years of working on bicycles, so this maybe just my strange perspective on things coming through, but the previous American Classic casings did not exude a feeling of ‘premium’ construction. This new tire does. At $45.00 then, I am impressed.

The Kimberlite is representative of a genre’ of gravel tires that feature minimal tread.

The tread is just what I’d want to see if my rides were done on a mixed bag of surfaces, or if my ‘gravel bike’ had to pull double duty as a roadie rig often. Yet there is that volume there, and the width, to pull off gravel rides. I’m becoming more of a fan of the ‘less is more‘ camp when it comes to tread design for gravel bikes. Tires like this, the Donnelly Strada USH, the Goodyear County, and the WTB Byway are tires that I feel fall into this vein.

I weighed the Kimberlites on my digital scale at 504/508 grams each. American Classic did not publish any claimed weights on their webpage that I could find. Width at 40psi was measured at 38.6mm. So, a bit undersized, but I will monitor these tires for stretch and see if we end up at the claimed 40mm later on.

Tubeless set up was a breeze, but these tires did fit pretty tightly on my Irwin Wheels Carbon Aon 35 rims. The tires aired up with a floor pump easily and the WTB sealant did not leak through the sidewalls at all after 24 hours, so that was a good sign. I will gauge air retention as the test goes on.

GT's Raleigh Tamland Two mounted with the American Classic Kimberlite tires.
Time to ride….

So Far… The new updates to the American Classic gravel tire range are a welcomed sight here. Just how these changes play out in actual usage we will see about soon. But the casings look and feel like a higher quality product versus the original American Classic tires.

The brown side wall treatment looks classy and not as ‘bright’ or ‘shouty’ as the tan wall versions. (But personally, I am a big fan of skin wall colors) Aesthetics aside, this is a tread pattern which should roll well and fast. I expect good ride qualities, and I expect these to resist punctures, although with a tubeless set up, this quality is less of a concern, to be honest.

The weight is a bit of a concern as is the under-size width measurement I got initially. Hopefully the weight is worth it and the tires stretch a bit. Stay tuned for an update coming in a month or a little more…..

For more information on the Kimberlite and the American Classic tire range see their website here;

Note: American Classic sent over the pair of Kimberlite tires at no cost to Riding Gravel for testing and review. We were not paid, nor bribed for this review and we will always strive to give our honest thoughts and opinions throughout.


Author: Guitar Ted

Guitar Ted hails from Iowa. Home of over 70,000 miles of gravel and back roads. An inaugural member of the Gravel Cycling Hall of Fame and Co-creator of Trans Iowa in late 2004- Guitar Ted has been at the forefront of the growth of gravel events and riding since then. Creator of Gravel Grinder News in 2008, he produced the premier calendar of gravel and back road events. GT joined forces with Riding Gravel in late 2014.

Related Articles

3 thoughts on “American Classic Kimberlite 700 X 40mm Tires: Getting Rolling

  1. The fast rolling center is a good idea. Reminds me of the smooth center strip of many 80s and 90s mtb tires. Question though. It looks like the area with (next to the center area) semicircular cones will trap a lot of small rocks, etc. How to you find that to be when riding?

    1. @martybike – Designs similar to this can, as you have noted, fling stones. This example wasn’t an issue that way in our gravel. However, a finer pea gravel or sandy surface may prove to be a different story.

Leave a Reply

Your email address will not be published.