SIMMO'S TYRE TIPS

If your car pulls one way or another when you let go of the steering wheel, chances are it needs an alignment. A poorly aligned car can cause several problems for you.

First, and most obvious, is badly wearing tyres. While you might have lots of tread wear left on one side of your tyres, you could find it worn down badly on the other side of the tread.

Secondly, you have increased rolling resistance. What this means is that it’s harder for your car to move if the wheels aren’t going in a straight line. And this means increased fuel use because the car requires more power to propel it forward.

Thirdly, it puts pressure on other steering components which can fail, costing you more money.

In summary treat a wheel alignment like an oil change; it is preventative maintenance. We recommend you have a wheel alignment every 12 months or 12-15000km. It costs $62 for a standard car, $72 for a 4WD and takes about an hour. Do you need to book your car in?

Wheel Balances

How do you know when your wheels need balancing?

The first thing you notice is that the steering wheel shakes as you drive along, usually at 60kph up to open road speeds.

What is it that's happening to make your steering wheel shake?

When fitted, most new tyres will have a slight heavy spot which is minimized by fitting the tyre's heavy spot to correspond to the light spot on the rim; the left over imbalance is remedied by fitting a lead weight, calculated by the wheel balance machine, to the tyre rim combination.

The reason your car shakes with an out of balance wheel is that as the wheel turns, the heavy spot when at the top of its rotation, is trying to lift the wheel off the road surface, and correspondingly trying to force the wheel down on to the road at the lowest point . To put that into perspective, 35 grams of imbalance at 100KPH generates approximately 8 kilograms of force trying to lift your wheels off the road.

All this going on at the wheels transfers back through the car's steering and to you holding the steering wheel.

It also puts extra strain on the car's steering and suspension, wearing out parts faster than normal.

Another possible explanation for a shakey car is that you have a separated tyre on the vehicle. What that means is a tyre that is starting to come apart, usually at the edge of the steel belt on the shoulder of the tyre. This causes the vehicle to shake at slow speeds and appears to improve slightly at speed. The reason for the slight improvement is the shake becomes more of a vibration at highway speeds. More about separating tyres.

How do you know when your wheels need balancing?

The first thing you notice is that the steering wheel shakes as you drive along, usually at 60kph up to open road speeds.

What is it that's happening to make your steering wheel shake?

When fitted, most new tyres will have a slight heavy spot which is minimized by fitting the tyre's heavy spot to correspond to the light spot on the rim; the left over imbalance is remedied by fitting a lead weight, calculated by the wheel balance machine, to the tyre rim combination.

The reason your car shakes with an out of balance wheel is that as the wheel turns, the heavy spot when at the top of its rotation, is trying to lift the wheel off the road surface, and correspondingly trying to force the wheel down on to the road at the lowest point . To put that into perspective, 35 grams of imbalance at 100KPH generates approximately 8 kilograms of force trying to lift your wheels off the road.

All this going on at the wheels transfers back through the car's steering and to you holding the steering wheel.

It also puts extra strain on the car's steering and suspension, wearing out parts faster than normal.

Another possible explanation for a shakey car is that you have a separated tyre on the vehicle. What that means is a tyre that is starting to come apart, usually at the edge of the steel belt on the shoulder of the tyre. This causes the vehicle to shake at slow speeds and appears to improve slightly at speed. The reason for the slight improvement is the shake becomes more of a vibration at highway speeds. More about separating tyres.

Some basic sound advice for choosing and looking after your tyres to get the best out of them and out of your car:

The first thing is to choose the right tyre for your car and its predominant usage; in other words “buy a tyre that meets your needs and type of driving”. But remember this also has to be balanced with the requirements of your vehicle too. Most mid to later model cars will need a reasonable quality tyre to deliver the performance they were designed for in the factory - putting a really cheap and nasty tyre might save a few dollars but may compromise the vehicle’s performance, especially in wet conditions. You would be surprised how much difference a good tyre makes over a lesser cheap one.

The types of differences you would notice would be in open road cornering, braking, accuracy when lane changing etc. The reason for this is that a good performing tyre will help the vehicle to do its job by not allowing it to under steer any more than the manufacturer has allowed for. Most of the cars we drive have a certain amount of under steer built into them, unlike a race car which is giving the driver a lot more input generally (as professional drivers have a higher level of skill than most of us).

So all that said once you have chosen your new tyres, maintenance is the key as with most things. Keep your tyre pressures accurate, keep your wheel balance and alignment up to scratch, avoid the pot holes on our winter roads, (but if you do belt a pot hole get an alignment quick, as you won’t know you have done any damage until it shows up in bad wear on your tyres). Nitrogen in your tyres is also a good idea as it keeps a constant pressure due to the lack of moisture. Dry Nitrogen can’t expand or contract due to temperature changes. It should also give a small fuel saving too, due to less rolling resistance through accurate tyre pressures.

If you are running straight air it would pay to check your pressures every 3 to 4 weeks. Nitrogen you can be more relaxed as it won’t leach out any where near as much as compressed air can.

If you maintain your tyres properly you will get maximum life and the best performance from them.

If your tyre pressures are too low, the extra friction caused by too low pressures makes your tyres run hotter which leads to faster wear. The tyres will wear on the outer edges if underinflated. You will have poor handling and your car will wander across the road with low tyre pressures. Your tyres will eventually fail if left underinflated for long enough. And that old thing again about rolling resistance - if your tyres are half flat your car needs more energy to move thus requiring more power (petrol to move it).

If your tyre pressures are too high, it makes for a very harsh ride and will cause tyres to wear in the centre of the tread rather than evenly over the tyre.

Too Low

1. Makes it harder for the tyres to move (increased rolling resistance - see above) and increasing fuel consumption.
2. Will cause the tyres to wear on the outside edges faster.

Too High

1. Makes for a very hard ride.
2. Will cause tyres to wear in the centre rather than evenly over the tyre.

If you're unsure what pressures to run in your tyres, call in anytime and we'll check them for you.

Rotating your tyres extends the tread life over the whole set, as it allows the set to wear out evenly.

If you get one bald tyre you don’t necessarily have to replace both tyres on that axle, but it pays to keep tread patterns and tread depth as close as possible for best handling.

You might hear the term “rolling resistance” used when it comes to tyres, and you might wonder what it means. Rolling resistance is an important factor in determining fuel economy and CO2 emissions. Put simply, rolling resistance refers to the amount of force required to power a tyre forward. Reducing this resistance means less fuel is required to power the vehicle, resulting in less CO2 being emitted into the environment. So another way to save on fuel is to fit the lowest rolling resistance tyres you can find and with that in mind, Bridgestone has brought out a range of tyres for precisely this issue. Known as ECOPIA, this tyre has been designed for least rolling resistance while maintaining premium levels of grip and handling. Another plus for this technology is reduced CO2 emissions from cars, as less power required to motivate the vehicle means less fuel burned meaning lower emissions.

Watch out - the warrant of fitness guy is getting tougher. As you may or may not be aware, you are not allowed to mix directional, non directional or asymmetric tyres on the same axle on your car. This makes good sense, as they all have their own handling characteristics.

But now the regulations say that the tyre's load rating must be the same or within 2 points, i.e. if your tyre has a load speed rating of 91V, you must fit a 91V or 89V or 93V tyre to be given a WOF. This is to keep all tyres on your cars as close to the same specifications and handling characteristics as possible and provide the safest drive for you.

This is not a huge issue for most of you as we fit compatible tyes as a rule, but if we do have to find you something outside the normal channels, bear with us and we will match a tyre up for you.

Tyre Tread Requirements:

Road tyres are required to have at least 1.5mm tread depth across 75% of the tread width around the whole circumference of the tyre. However, if the tyre has 25% worn area, then we would recommend replacement.

To locate your tyre size, look on the sidewall of the tyre. There will be a series of 3 numbers, e.g. 205/65R15.

These relate to:

• The width of the tyre (section width of the tyre in millimetres)
• The aspect ratio ('height' from the bottom of the tread to the rim - as a percentage of the width)
• The rim size (diameter of the wheel rim)

Directional Tyres

This type can offer improved highway performance at higher speeds, in conjunction with a good tread compound. Tread is usually in arrow form and can only be fitted one way.

Asymmetric Tyres

These also offer a good performance tread. They have an inside and an outside, which means tyres can be put anywhere on the car.

Non Directional Tyres

This type of tyre is as said, and can be fitted anywhere on the vehicle. Non directional tyres are less likely to track or follow undulations in the road surface.

Used Tyre Issues

Recently I had a lady come in to ask my opinion on a tyre that had disintegrated on a trip to Auckland. She had purchased the tyre from a used tyre dealer. The reason she was getting another opinion was the fact that the tyre had come apart and torn half the valance off the car’s front end. It’s probably a $500 plus panel shop repair to fix, and the used tyre dealer wasn’t interested in paying for the resultant damage.

My point in this case is that on inspection the tyre turned out to be a 9 year old Japanese imported used tyre and beyond its intended “on vehicle” lifespan. It had failed due to a separation of the plys in the tyre’s tread - which would have been helped along no doubt by the tyre sitting around, possibly outside in the weather, for a long period of time.

So watch out for that “cheap” used tyre bargain - it can be an expensive exercise.

Some of these used tyres that are unsafe can be on a vehicle’s spare rack, ie on the back of a 4WD. The tyre looks good, brand new looking tread etc, but your 4WD vehicle might be a 1996 Nissan Safari or something similar, and that tyre may have been on the back since then, making it 14 years old. A tell tale sign to look out for is weather cracking in the tread area, which looks like old age wrinkles in the rubber (I don’t know about those yet ha ha).

Again this also leads on to the second hand and old new tyres that are for sale. What are you buying ? Potentially a 10 year old tyre that could be in an already deteriorated condition going on the family car. When you also consider in that 10 year plus period, the vehicle would have most likely had 3 or 4 sets of tyres fitted to it.

It’s quite simple to tell how old a tyre is by the serial number. Modern tyres will usually have a 4 digit number, i.e. 1012 which would mean it was made in the 10th week of 2012. No tyre manufacturer will warranty a tyre that is more than 5 years old because of the perishing and deterioration that can happen with the rubber past that time.

Firstly a tyre that is separating means a tyre that is starting to come apart. A tyre that is starting to separate will show up as a wheel balance type problem, where the car's steering wheel will shake in your hand while driving, or you will feel a vibration through the vehicle as you drive.

The easiest way to tell whether you have a wheel balance problem, or a separating tyre is the speed at which it occurs.

Wheel balance will not usually show up when you are driving at city speeds e.g 50kph etc. A tyre that is starting to separate will - it makes the car appear to wobble at slow speed from the front or the rear of the vehicle, and will appear to improve as the speed increases and become a vibration. The reason for this change is as the tyre rotates faster on the car the wobble gets faster and doesn't seem quite so bad.

When I suspect a separating tyre on a customers car the first thing I will ask is, "will you notice the problem if you drive up the street to the roundabout?" If the answer is yes then we most likely have a tyre that is in the process of failing.

Tyres can separate for a number of reasons

As your tyres wear down there is less tread to protect the body plies of the tyre, a stone or nail or other sharp object pierces the tyre, not necessarily right through but into the body ply of the tyre. Moisture can now get in to the cut and as the tyre heats up the moisture in the tyre expands causing the internal structure of the tyre to start coming adrift. A nail or foreign object left in a tyre can also cause the same problem by providing an entry for moisture etc.

As you may be aware these types of failures seem to happen to used imported or cheap tyres a lot more often than better quality tyres. The reason for this is that the better tyres are constructed with extra cap plies and more under tread rubber in the tyre to protect the tyre against the harsh stone chip that we use on our NZ roads. A large percentage of cheap, imported tyres that come into NZ are not constructed with this in mind and thus a lot more prone to this type of failure.

If you think you have a tyre that is failing in this way, change it as soon as possible as the tyre will eventually come apart and you will have steel wire and bits of tyre peppering your car and any one else's in range.

And if you’ve ever wondered what a separated tyre looks like, check out this photo! This person had 3 tyres like this on their vehicle. You can see that having tyres like this on your car is an accident waiting to happen – it’s the only thing between you and the road!

Every day people ask us for prices for the tyres on their car - the first thing we need to know is the type of driving the vehicle will be predominantly used for; in other words is the car doing out of town trips on a semi regular basis or is it literally a shopping basket.

The reason for the difference is at round town speeds (30-50Kph on average), the performance expectations of the tyre are considerably less than if driving at 100Kph on the open road.

Your car, 4WD etc is designed to perform to its optimum level with tyres equal or above the level that come fitted on it when it was new, so if you go out and fit inferior tyres to it you run the risk of compromising the vehicle’s handling characteristics. As I write this we have just done a nitrogen fill and wheel alignment on a late model European vehicle that had been fitted elsewhere with probably the cheapest Chinese tyres you could find. That vehicle will not handle anywhere near its potential, especially in wet weather and at higher speeds. A low level tyre on this sort of vehicle will under steer - in other words it won’t steer in to the corner accurately and hold a clean line. It can also break traction during cornering when pushed a little. Conversely, a tyre more suited to the vehicle will do its job without giving you cause to worry. The reason for this is in the construction of the tyre - a tyre for say an SS Commodore needs to be constructed to deal with the power and weight of the vehicle and have a tread compound that is sticky enough to harness the power and put it on the road as well return a reasonable mileage.

Vehicles now ask a lot of their tyres due to increased horsepower, handling ability etc. The days of getting 80 to 100,000km from car tyres are gone with the low powered, basic vehicles they were fitted to.

In summation, the higher the performance tyre you buy, the better the handling will be. A good level, family car tyre will suffice in most cases, but for the driver who likes to push the car a little more, then a higher level performance tyre will be what is required. With this type of tyre though the mileage returned will be a little less than the family car tyre. This shouldn’t be an issue to the person that wants a higher level of performance from their car.

Original equipment tyres are the tyres a car comes fitted with as new from the factory. In some cases these tyres can be a little more expensive than some other branded ones, but in most cases these OE tyres have been fitted to the car for a good reason - mainly the fact that they have been tested and approved by the vehicle manufacturer for good all round wet and dry road handling, low road noise, on the vehicle they are fitted to.

This is not to say you can’t buy a tyre other than the OE one that is up to the job, but just means you know they are right.

A good case in point for the OE tyre issue is the later model Holden Commodores fitted with the 245/45-18 and 245/40-19 Bridgestone RE050A tyre. This car has a stability and traction control function which does not like other brand tyres. We had one particular car of this model fitted with very cheap Chinese tyres that could not be driven properly as the Stability traction control function kept on activating during normal round town driving, and was so bad the customer took nearly new tyres off and replaced with the OE ones. Once replaced the problem disappeared. That was an extreme case but it does show that as cars get more technically advanced the tyres need to be up to the job.

These days there are a lot of 4WD vehicles on our roads and a swag of tyre choices to go with them, so what I want to cover here is just what tyre you should fit to your vehicle and why.

One of the things we hear a lot is “I do quite a bit of off road driving so I need a pretty chunky tyre”. While this may be true, you still have to take into account the other potential uses of the vehicle, ie, is it used as the family car as well - maybe other members of the family use it for varied on- highway tasks and day to day driving.

If this is the case you have to compromise a bit on your tyre choice and find a tyre that is capable on both counts; in other words a tyre that can get you out of a sticky off road situation but behave with good on road ability.

Most of the tyres we fit to 4WD vehicles fall into the 80/20 category, which is a tyre that is 80% road use, and capable of 20% light off road use. The next would be in the 60/40 range, still reasonable on road but its capability off road (ie 40%) is considerably better in muddy conditions.

Up from these tyres you head in to the pure off road type which offer very little on tar seal, wet roads etc. This type of tyre can be quite dangerous on a wet highway as they don’t have sipes in the tread blocks. Sipes are the cuts in the tread blocks that are there to disperse water from the tyre so as to prevent aquaplaning - where water prevents the tyre’s surface from getting grip on the road.

So when you come in for your 4WD tyres we will ask you a few questions about what you require and then recommend a tyre that should do the best all round job for you and be safe.

Examples of some of the different types of 4WD tyres we have available:

Bridgestone D684 - highway use tyre

Firestone Destination A/T - 80/20 tyre

Cooper STT Maxx - heavy duty mud grip tyre

This tip is for the car restorer/hobbyists among us.

Have you ever thought it would be great to restore your old car back to original right down to the type of tyres it came on? Well you pretty much can in most instances; tyres for a large portion of these vehicles are available through us via the importers we deal with.

As with a lot of products like vintage tyres, if you want the genuine article they will not be the cheapest tyre you will ever buy but the satisfaction of having the correct size and type on your vintage or muscle car restoration is immeasurable.

Allied to this there is a large range of period correct rims, alloy, chrome, and steel available for American classic and muscle cars. Most of these tyres and wheels are available on indent with an approximate wait time of 8 to 12 weeks.

I realize this will be only a small portion of you that do this type of thing, but I guess the point we are making is no matter how weird or strange the tyre size type might be give us a go as we can probably help you. I have heard many times from customers that they had tried every where and we were the only ones who could help!

30 years in the trade has its advantages - I know where to look!

Nothing too technical, just some sound advice to save yourself time and money.

Firstly get in the habit of checking your tyre pressures regularly, You can bring your car in for us to check or you can do it yourself. I check a lot of tyres here and quite often find tyres that should have 30 psi in them have 18 to 22 psi or worse. What this does is wears your tyres quicker as the friction on the underinflated tyre increases the running temperature of the tyre, leading to premature wear and also irregular wear. It can also make the car harder to steer, possibly pulling one way or the other.

Another good idea is when you hear noises or feel the car handling a little differently, stop and check your tyres for punctures. I have lost count of the number of times I have heard someone say "I thought I heard something" or "The car seemed to wander a bit". Just hop out and give the tyres a kick - it may save you a lot of money.

Lastly, if you don’t think you will check your tyres that regularly you can always have them filled with Nitrogen which holds its pressure considerably better than air. It offers benefits like a smoother ride and better handling through consistent pressure, and at only $22 for 4 car tyres it wont break the bank.

Why should I spend $150.00 on a good quality new tyre when I can get a budget one or used one for $100.00 or less?

When your car was new it was designed to run on the optimum tyre for the vehicle, in other words its handling characteristics were set up with a certain type and construction of tyre for the car.

If you then fit inferior tyres to the vehicle it will probably not perform to its potential ability on the road, which translates into poor cornering, sluggish lane change, road noise, etc.

A poor handling car can also help to make passengers car sick.

By fitting the best tyres you can afford, you keep your car's performance where it should be, which is the safest and most comfortable way to be.

As well as the fact that used or inferior tyres may not handle particularly well, there is also the issue that they won't last as long, due to different tread compounds, and tyre construction for road surfaces in foreign countries. NZ road surfaces tend to be harsh compared to a lot of other countries in the world. We use a coarse stone chip which can also translate into excessive road noise.

I want to give a few examples of how far tyres on your car have come in the last few decades.

The original Toyota Corolla came on whopping 600-12 cross ply tyres, which were a little bit wider than your average wheel barrow tyre and about the same amount of road holding ability. Today the venerable Corolla comes out on a 195/60-15 which is a wide low profile much higher performance tyre.

When I started in the trade in 1979 we still sold a lot of the original crossply type tyres as radials were still in the early stages of acceptance and a more expensive option. The radial tyres that were available then were the fabric type (not steel belted as now). These days the fabric tyres are also few and far between, although you do see them hanging from trees as swings (you can cut through the tread area to make the swing).

Next step was the steel belted radial tyres that we all use today. These tyres are standard on every car and are evolving regularly. Tyre sizes on cars are getting larger and the profile of these tyres is getting lower for the higher performance of the vehicles they are fitted to.

The first Holden Commodores came out on 175-13 high profile tyres and a performance Commodore was fitted with 195/60-15 tyres; now the high performance Holden is fitted with 245/35-19 tyres, very wide, very low profile.

That is just a snapshot of the changes in type and sizing of tyres these days.

When I first started in the tyre industry we sold mag wheels but mainly 14 inch; these days we regularly sell 20 inch wheels for cars and 4wds - I have seen a 4wd Hummer on 25 inch wheels.

With the condition of our roads at the moment you need to be extra vigilant as to what you drive over, through, or round. Some of the potholes on the roads have potential to seriously damage the wheels, tyres and suspension on your vehicle. We have seen over the winter months dozens of damaged wheels and tyres due to this – which costs a lot of money to put right. Wheels have cracks and large dents requiring an engineer to straighten them; wheel alignments need doing too as suspension components can be bent or put out of specification if hit hard enough. A lot of this damage gets picked up at WOF time which causes delays and inconvenience. So when you’re out there driving stay alert and try not to drive over potholes if you can help it.