It's strange how you get weird looks from some people. The other day I visited a wheel and tyre outlet where I set about weighing a heap of them on a spring balance in the name of AutoSpeed research. While most people were sitting back in the rickety waiting chairs sipping free coffee and reading the day's newspaper, there was me looking like some kind of freak with nothing better to do. But amid frantic mass-measuring, I spied out of the corner of my eye a set of 16x7 inch WRX rims poised proud on top of a rack. Hmm, the perfect slip-on upgrade over the Liberty's standard 15x6s. I wondered how much they wanted for them, given that I'd supplied them with such rich entertainment for nearly half the day. The answer was a mere $500 for the set - which I thought wasn't too shabby, considering the new price from Subaru is around $800 each...
Upon returning home that night, I sussed out the tyre dimensions that would be required to maintain the same rolling distance as the standard 15s. As it turns out, keeping the same 205-width tyre, the closest diameter to standard was the 55 series 16-incher - which was just less than 1% oversized.
No problem, I thought, I'd just go out and quickly snap up some readily-available tyres. But a last-minute inspection of the car's tyre placard revealed a problem. The '92 Liberty RS needs a load index of 91, which represents 615kg. So what's the placard specified load index? It's the minimum required weight carrying capacity of a tyre as determined by the vehicle manufacturer. The guidelines for manufacturers are set by the Australian Tyre and Rim Association, and the Japanese Automotive Tyre Manufacturing Association.
And, of course, the only tyres that rose to this 91 load rating turned out to be few and far in between - and starting at around $300 each, they weren't especially cheap either.
Digging for the impossible treasure, I dragged myself around some of the local importers that bring used tyres in from Japan. My success was mixed as I found only the odd suitable tyre, not pairs - but the words of wisdom from some of the tyre people really had me gasping. Some shrugged their shoulders at the concept of load ratings, suggesting I'd never ever have legal or insurance hassles fitting 90 (or less) indexed tyres. On the other hand, others stated point-blank that I could only fit 91 (or higher) rated rubber. I also came across the highly illegal suggestion of simply sticking a different tyre placard inside the door jamb...
One guy I know owns a Liberty RS with big 17-inch aftermarket wheels fitted, but when I looked through every tyre brochure on the face of the Earth, there wasn't even one tyre that met the load requirements of the car. So I guess it was obvious what his view on load rating requirements were - or perhaps he is unaware.
Delving a little further, I found out that the later model Liberty (only slightly smaller) has a load index of 88, and the Mitsubishi Galant VR-4 (with similar mass and power to the RS) gets away with an 87 index. That'd be right - I've gotta have the difficult one!
Eager to find a less financially strenuous way out, I thought I might talk to the "experts" on what the story was with fitting lower than specified load index tyres. My next phone call was to the local Road Transport Authority. Upon explaining my exact details, the ever-knowledgeable young buck at the other end of the line told me unequivocally that all I needed to do was to weigh each corner of the vehicle, and bingo - that was the load rating I needed. Hmm, I wondered if this guy was having a lend of me; maybe he just had a strange sense of humour. Probing for some more info, I asked what would happen if I was to hook a 20-foot trailer boat onto the tow hitch. "That wouldn't make any difference to the weight over the car's wheels" came the abrupt (and apparently serious) reply. So I ended that particular phone call there and then...
Another person told me to try talking to my insurance company. On the phone again, I asked my insurance company on their policies regarding the matter. Their answer was that they did require a full manufacturer's rating, but if I wanted to check on any technicalities to ring their legal-eagle contact within the aforementioned RTA. I was then kindly given the person's name and phone number. But - wait a minute - it was the same number as the previous weigh-all-four-corners guru!
Ah what the hell, I thought, so I dialled the number again expecting to have a nice chat with my ol' mate. However I heard a different voice coming down the line this time - a much more mature voice. It actually turned out to be the man I was after. I (again) explained the dilemma, and the gentleman seemed very receptive to my words. He promptly searched through their official documentation and confirmed what was his suspicion; you cannot in any case under-cut the placard number. Plain and simple; no ifs or buts.
He also acknowledged that there were many cars driving around with under-spec tyes fitted, but pointed out that in the event of an accident, a keen-eyed accident or insurance inspector might be able to put you in a very awkward and expensive position...
So to everyone, if you're not sure what the load index of your car's tyres are - please check it out! It might end up saving you a lot of money if your insurance company finds a way out of paying out a possible claim.
And me? I guess I'll have to keep saving for those damn 91 index tyres...
A mate of mine recently purchased a leaded-fuel 1984 Mitsubishi Cordia turbo with a re-conditioned engine and bog-stock everything. After he'd driven it for a day or so, we spoke about its on-road performance. To my surprise, he sounded totally blown away - it was apparently a lot faster than his now-sold 15.6-second Charade turbo. But how could that be - it should be slower, shouldn't it? I kind of implied to him that he didn't know which way was up, and that he just thought it was faster. So the next thing I knew he was on his way over to prove it.
After downing a quick meal, I found myself buckled into the Cordia's passenger seat waiting for the supposed almighty push in the back. As the engine revs rose over around 3000 he planted the pedal and, boy, was I surprised! The mid-range pull was far in excess of what I was expecting, and the top-end hit didn't drop off much either. That was, until the engine suddenly cut out. And I could tell it wasn't the suspected ignition system problem - that was an overboost fuel-cut, my boy! We pulled over and inspected the wastegate actuator line, canister and turbo unit. Nothing seemed amiss, except that the actuator rod couldn't be moved by hand - that's because we couldn't grip it well enough, we thought.
A couple of weeks later, the problem (if you can call a fast car a "problem") was suddenly solved. It was discovered that the wastegate valve was completely jammed shut! With unlimited boost on tap, no wonder it went so hard!
Even after that turbo glitch was remedied, his particular car still seemed to go a bit better than standard. It wasn't until around a fortnight ago that the head gasket unfortunately blew, unveiling Part Two of the mystery. The Mitsubishi engine, having been previously re-built, was put together with no balance shaft! There was the drive belt and cog still in place - but no shaft to turn. Wow. I thought most engines (especially larger fours) ran like pigs without their balance shafts, but his one just seemed to run like one with a slightly coarse design characteristic. I guess the Cordia engine must be very well balanced to begin with.
No doubt, he'll keep searching around under the bonnet for other oddities - who knows, next he might find a hidden nitrous nozzle!
