PEOPLE FORGET how crucial tyres are – they’re arguably the most important part of the vehicle. So looking at things such as inflation and pressures is worthwhile. Ninety per cent of people get this wrong and don’t check it often enough.
You can lose air pressure for a huge numbers of reasons. One of the biggest fallacies is the Schrader valve is your only seal. Getting a good modern valve cap that has an O-ring inside it is worth doing –that’s what they use in the racing industry. Make sure your valve caps are always there.
Keep in mind air expands with rising temperatures, so the pressures can go up quite noticeably on a trip. Meanwhile, you should be checking them at least fortnightly.
Let’s talk about checking those pressures. When your rubber is over-inflated, it will wear in the middle. If it’s underinflated, it will be worn on the outer edge. You might even feel a tendency for the car to ‘walk’ as you change direction.
And the right levels? You need to start with the tyre placard on the car (often inside the driver door) or in your handbook, assuming everything is still stock and the car ever had such things. Disregard the info on the sidewall of the tyre itself, as that talks about maximum ratings, not what you’d normally use.
If there’s no maker info, there are some rules of thumb. A common starting point is 32psi, and that’s a level where a lot of cars are working well. To make it a little more efficient, we’ll often increase that pressure anything up to 6psi while we’re servicing a car.
What that does is it reduces the rolling resistance, it’s not so high a pressure that it’s going to wear the tyres, and it’s enough to make a little difference. It will turn a little easier, roll a little easier – nothing radical, but it all adds up and can improve your economy a little.
Of course there are hundreds of brands and offerings out there. I can’t say the cheaper brands are bad, but the better brands are just that. It really can be worth talking to your tyre people when you get them changed and make sure they understand what you’re after. A grippier tyre will tend to have a shorter working life, but that’s often a compromise worth making.
Keep in mind too that the sorts of cars we’re driving often need specialist advice, so don’t be afraid to hunt out someone who understands classic cars. At times there are options out there for older vehicles that your average corner tyre shop may not always be aware of.
Something to keep in mind with a project car is just what the brake/wheel/tyre package should be. You don’t want one completely overwhelming the other. For example we just built a nice EJ wagon with a V8, rack and pinion steering and updated disc brakes.
What we were careful to do was not ‘overbrake’ it. That is, fit giant rotor and caliper packages that are going to overwhelm the tyres. The trick is to look for improvements but maintain some sort of balance. And keep in mind you may need much, much, stickier tyres to cope with all that extra stopping power. We did recently have a customer car lock up all four wheels and give us a fright during a braking test and, once we changed our underwear, we went out and got it better rubber.
In turn, giant wheels with ultra-low profile tyres may look great, but may not work as part of your suspension package. Remember that the tall sidewalls on older cars are actually part of your suspension. All those components need to ‘talk’ to each other.
So, remember to keep the pressures up and be nice to your tyres…