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(By Grant Spolander)


A couple of months back, I spoke about tyre balancing and the fact that bigger, heavier tyres are often harder (and more expensive) to balance than OE fitted units. This raises an interesting subject − namely, the costs of up-sizing your tyres.

The heart wants what it wants, and once it settles on an idea it’s near impossible for the brain to do anything about it. Logic has left the building. 4x4 tyres are a great example.

When the thought of up-sizing one’s tyres pops into mind, the first consideration is fuel consumption, along with the question: “How much more fuel will my 4x4 use?” But that’s like having kids, and only worrying about the price of diapers. The real monetary abyss lies in the mods that make a tyre up-size possible. I’ll use my own tale as an example…Once upon a time there was a foolish man who bought a 4.0-litre Jeep XJ. He then decided to modify the vehicle and was financially broke forever after. The end.



Okay, let me go into more detail: I bought the Jeep stock standard and swore that I would NEVER go bigger than a 30” tyre (which I’d had fitted shortly after purchasing the Jeep) and a 2” suspension kit. I then took the vehicle on a challenging 4x4 trail and it became painfully obvious that the Jeep’s number one limitation was ground clearance; so the thought of a 31” tyre popped into mind.


Once again, the vehicle would require more lift to allow for the bigger tyres, so I imported a kit from the States, fitted 31s, and swore to myself that the journey would end there. No more upgrades! No more up-sizing!


At this stage, 31s were considerably bigger than the Jeep’s OE size of 28”, so the 4-speed auto box was battling with the larger diameter tyres. Enter: a diff ratio change.


The Jeep’s standard gear ratios were 3.55, so the next step up was a 4.1 ratio. However, the folks at 4X4 Traction were selling a set of secondhand (4.56) gears, along with a beefier rear diff, Eaton E-locker, and upgraded side-shafts. So I took the plunge, pillaged my bank account, and like any true off-road addict, I lied to my wife and convinced myself it was all necessary.


But it didn’t end there. The 4.56 ratio now meant that the Jeep was over-geared for 31s... so the thought of 33s arrived.


I can’t remember all the ridiculous justifications I made to myself, but at this stage I was wondering if a heroin addiction wouldn’t be a cheaper weekend habit. Nonetheless, the 33” upgrade went ahead, along with pipe doors, massive body- and chassis modifications, a custom front bumper, winch, and exterior roll cage.



It was finally over. I breathed a sigh of relief and took comfort in knowing that I’d reached the end of the road: the Jeep’s modifications had exceeded the boundaries of my imagination.


I felt a profound sense of completion and an almost Jerry-Maguire-like epiphany: “Jeep, you complete me.” My wife wasn’t too pleased with this statement, but she couldn’t deny how much our kids loved the “new” Jeep. All was forgiven.



I felt so positive about the vehicle that I played with the idea that the journey had been worth it. It hadn’t been a mindless addiction: it had had a purpose, an end, a final metamorphosis and transformation!


A few months later, I found myself standing around a braai with a few 4x4 mates when one chap asked: “So, Grant, I’ve been thinking about down-sizing my tyres. Any chance you wanna swop your Cooper 33s for my 35s?” My mouth hung open like that of a relapsed drug addict and I felt a sudden urge to scratch at something. “Damn you,” I said, “Damn you and your 35s.”




I’m sure many of you have at some point considered a tyre-size increase, but before you venture down this road, I thought I’d mention just some of the obstacles (costs) you may encounter along the way. To be clear, I’m not trying to discourage you; that would be hypocritical as I’ve just started a new project (read: addiction). But that’s between you, me, and potentially some debt collectors. Here’s the list…


Suspension upgrade (bigger tyres need better suspension)

Suspension lift

Custom control arms

Custom track bar

Slip-Yoke Eliminator

Wider wheels and more off-set

Larger fender flares

Larger wheel arches (trimming)

Major chassis modifications, welding and trimming

Extended brake lines

Transfer case drop-down kit

Custom mud flaps

Upgraded side shafts

Gusseted diff housing

Better brakes

Diff ratio gear change

Diff carrier upgrade

More engine power



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