In the early spring of 2018 I purchased my first set of 37" tires. They were BF Goodrich Krawlers in 37x12.5 R17. I chose these tires because of their incredible resilience and toughness and everyone mentioned how incredibly long they last. How could I go wrong with a long lasting, nearly indestructible tire? That's why I thought I'd give them a go on my overland Jeep, despite that being a very unconventional choice, with the majority of overland rigs rolling on BFG All Terrains. (This is based on the findings of my vast, in-depth research, using science).
My first impression of the Krawler was that they looked super rugged and aggressive, so I was expecting a lot of road noise. I was very surprised when I found out that they weren't any noisier than any other mud terrain tire I had tried before. Now this isn't proven scientifically with a decibel meter or anything fancier than my own two ears. This checked my first box. After all, we live in a paved world. I read some complaints that these tires wouldn't balance well, however I didn't find that to be the case.
OK so let's get down into the nitty gritty of how these tires performed. A few statistics might help at this stage: I drove an approximate 20.000 km on them, maybe a bit less, over the time of about 9 months. This is not a long time, but I'll get into the reasons why I sold them at the end. However this was enough time to test them out in all conditions, pavement, mud, rocks, gravel, sand, water, dirt, snow and ice, as well as on a long 2000km round trip on highways to Ontario! Now they are L-rated for speed, which means no more than 120km/hr, so it's a good thing that modified heavy Jeeps on 37's don't really go much faster than that, so that wasn't really a big deal. Although I must admit I probably did 130 downhill at some point and they didn't explode, so we're good! I was expecting to see a visually noticeable amount of tire wear after that trip, but compared to the spare tire, this was not the case. For pavement use and tread life, I rate them a 5/5.
The remainder of the time on trails around New Brunswick from the sandy beaches in the South to the rocky trails in the North, these tires were dealing with everything in between. So how did they do in sand? Well for any sand driving, tires need to be aired down. The Krawlers are quite a soft tire, yet with their 4 Nylon sidewall plies, they air down well without bulging out too much. The massive square lugs are quite wide apart, much wider than regular mud terrains and this made them very good diggers, giving them great traction in sand. Not once did I feel like I was going to bog down or get stuck while driving on the beach, while others did! Of course a little common sense also helps and preventing unnecessary wheel-spin is one of those things that help. Wet sand can be quite sticky and often you see All Terrain tires with their narrow gaps between tread fill up easily in sand and mud and nothing shy of highway speeds is voiding them. That problem does not exist for the Krawlers with their massive spread out lugs, no amount of sand will accumulate in there. So besides rock crawling and driving on pavement, they are a great tire for anyone that drives a lot on sand. So in this element, they get another 5/5.
A very common theme here in NB is mud and water. Well once again the widely spaced lugs really help in these conditions. They rarely ever filled with mud, and when they did, some skinny pedal helped get rid of it pretty easily. Compared to the KM2's I had before, that were actually designed as a mud tire, where the Krawlers have been designed to climb dry rocks in Moab, these ones have performed better than the KM'2s. However, the massive lugs are not siped, which makes them very stiff, and perhaps therefore a bit inferior to the Cooper STT Pro's in mud for instance. They are however quite soft and do a very good job at swallowing up rocks and roots etc. The lack of sipes also makes them slightly less effective on wet roads as say a Goodyear Duratrac. For this reason, in wet and mud, I rate them 4/5.
How about gravel and dirt roads? Well I'm pretty sure any tire other than a street tire is perfectly capable of traveling over gravel and dirt so I'm not going to be spend a lot of time discussing this. However, peace of mind is a big deal, especially on an overland rig where reliability is important, you can't be late to arrive at camp or else won't have enough time to cook your gourmet 5 course meal on the skottle. With the Krawlers I never had to worry about missing out on my 5 course meal because there is literally next to nothing that will destroy this tire while blasting down gravel roads at Mach Schnell. So here's another 5/5 for this category.
Over to snow and ice. As mentioned, these tires were designed for ROCK CRAWLING, but they are still categorized and labeled as a M/S (mud and snow) tire. They are capable of getting the Jeep through deep snow for the same reasons they do well in mud and sand. However snow covered roads or even icy roads, these things are hockey pucks! In fairness, there isn't much any composition of rubber can do on ice unless it is spiked, however these have literally zero grip and even just touching the skinny pedal very gently on icy conditions makes these spin. However on snowy trails, aired down, these will do the trick. It's the getting to the trailhead or getting home part that's not so great. For this reason, they are not a great tire for an overland vehicle that sees any winter driving. And for their poor performance in snow I rate them a 2/5.
Ok so how how do the Krawlers do on on rocks? Do you really have to ask? This is their element, this is literally what they were made for. They have won more rock-crawling championships than all other tires combined! They stick to rocks, they mould around rocks and grip them and spit them out. They are rock eating monsters! There is a reason you see these a lot around events like King of the Hammers or rock bouncing competitions (yes that's a thing apparently).
That brings me to the conclusion. Overall these are great tires, they get through a lot, they last a long time, they are very puncture resistant, and they look great. However, here are the downsides: They only make them in 2 sizes because BFG keeps saying they will discontinue them, however that's been a few years and they still haven't, yet leaving only 37x12.5 and 39x13.5 as options. They are pretty terrible for winter driving unless they are on a trailered dedicated trail rig. Oh and did I mention that 1 of these tires costs $700 CAD?! Yeah....
So why did I sell them? Well the answer to this question is a very superficial one and that is that in my personal opinion, 37" tires are too tall to be only 12.5 wide, leaving them looking too skinny. This is literally the only reason I switched to a 37x13.5 and Cooper offered this size, and having had a great experience with Cooper before, and the STT Pro's being a great looking tire, the choice was and easy one for me to make.