The $500 Nail (Or Why It's A Good Idea To Change Tyres In Pairs)

Recently I mentioned getting a nail in the rear tyre on the GSX-R, and how I could have been stranded on the side of the road (What Do You Do If You Get Stuck On The Side Of The Road). Some of you even thought that my enthusiastic mention of Dave sounded a bit like an ad for him - yeah Ok, I guess I got a bit carried away but hey, think about getting stuck somewhere and you’ll remember him .

Anyway, back to the tyre story…

With a new tyre on the rear of the bike I went for a ride this week. Now, experienced riders won’t be surprised to know that the bike handled like the worst thing that had ever hit the roads! As the bike tipped into a corner it would hesitate, drop - and then give a big head shake.

For the sake of newer riders or those who have never ridden on mis-matched tyres lets explore what I had done.

The front had a Dunlop that had done around 6,000 km - about half the life you’d expect to get out of a sports tyre so I was hoping it would be Ok and I could save myself some $$. But the tyre had done a reasonable amount of track work, was looking a bit shabby and the profile was definitely knocked around. On the rear was a nice new Michelin.

I had actually turned a very well handling sports bike into something that had the potential to be quite dangerous

The things I had going against me here were:

• firstly there is a difference in the profile between tyre brands and even different types of tyres from the same manufacturer which will cause the front and rear of the bike to want to turn in at different rates
• an older tyre mixed with a new tyre will make this worse, especially when the older tyre is on the front
• the more difference in wear there is between the two tyres the worse the problem will be
• the tyre on the front was a harder compound than the rear, so I would have had less grip on the front than the rear as well - a very dangerous situation!

I had actually turned a very well handling sports bike into something that had the potential to be quite dangerous had I been doing any reasonable speed. The lesson (that I should have known) is that even though there was enough tread left on the front, it was far better to change both tyres. So it was off to the bike shop to put a matching tyre on the front.

Tyre manufacturers match front and rear tyres so they work together as a set. As the tyres wear and the profile changes (as long as they are wearing at a similar rate) you will notice a difference in how the bike turns in but they will still work together well. If you were very unlucky and had to change a tyre early in the life of the set you will normally get away with changing just one, but the further you’re into the wear cycle the better it is to change both. And it’s never a good idea to have different brands or different types of tyres on each end of the bike. They do it in racing but we’re talking road riding here.

And one more thing that, once again, experienced riders will know about but it’s good to mention. New tyres are coated with a very slippery protective wax. There are so many stories of people putting new tyres on their bike and crashing it in the first 20 km - I even heard of a guy crashing as he turned out of the driveway of the tyre dealer. Even though the mechanic who fits the tyres may take a lot of it off with a solvent, there is nothing like scrubbing the tyre on the road to remove that coating. So you need to take it gently at first and gradually increase the lean angle as you go through corners so that you progressively scrub the wax off.

The GSX-R now has a couple of nice new Michelins on it and is back to handling like it should, and that nail cost me around $500 all up. But when I think of how badly it handled and how dangerous it could have been I guess it’s a small price to pay … well that’s what I’m telling myself until the credit card bill comes in .

Safe riding!

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