Tyres sizes are normally listed with three numbers like 195/55/15. The first number is the width of the tyre in mm. The second number is the profile depth as a percentage of the width. The last number is the wheel diameter in inches. To convert the three numbers into rolling diameter in mm use:
Diameter = 2 x width x profile / 100 + 3.14 x 25.4 x wheel size

For recommended tyre sizes I looked in "Modern Engine Tuning" by A. Graham Bell (bought it at MotorBooks). On page 237 he gives his opinion on what's best for a 2L engined small car.

Minimum tyre: 185/70
Handling/Ride tyre: 185/65, 195/60
Handling tyre:195/55
The performance tyres are wider and the contact surface is closer to the rim of the wheel ie: the tyres are low profile. In order to maintain the correct rolling radius then larger diameter wheels are necessary. Fitting lower profile and wider tyres can increase the cornerning grip, reduce wall flex and therefore improve handling. Bump absorbtion will be worse though, so ride comfort will be lost.

The 8v GTE has 185/65/14 as standard ie: a performance/comfort tyre on 14" wheels. I looked in the ProTyre catalogue. They've got a handy table of what wheel/tyre sizes will work and keep the correct rolling radius. For a 185/65/14 tyre the rolling diameter is 580mm. If I wanted to retain this diameter then the options available are:
195/55 R15 (good), 205/50 R15
195/50 R16, 205/45 R16, 225/40 R16
205/40 R17
Therefore 195/55/15s would be the handling tyre size.

At first I tended to go for middle ranking big names such as Goodyear and Pirelli. First off I had Pirellis on the front. They cost £55 per wheel balanced and fitted at Protyre. Next up I tried some Goodyear tyres at £75 total for both fitted. They were quite reasonable but didn't last too long. But at that price I wasn't too bothered. Next time I tried Goodyear Venturas. They cost a tad more (£85 total for both fitted). On the road they seemed about the same as the previous tyres. My local tuning place told me that Goodyear Venturas were "crap". Toyo Proxies were their favourites.

After fitting strut braces I started to realise that the tyres were limiting the handling. I was asking around on the MIG bulletin board when I was told of someone selling some Cavalier Sri 15" wheels for a good price. Another MIG person recommended the wheels, telling me that they look really good on the MK2 Astra. I wasn't sure about the looks, but the handling improvement was enough to tempt me.

Since the wheels were from a Cavalier, they had 185/65/15 tyres fitted. That meant that the rolling radius was larger. All the same, I fitted them because I was curious as to what they would look like and what sort of difference it would make to the handling.

I still wasn't sure about the looks, but I could feel a difference handling wise straight away. Suitably encouraged I went round to ProTyre the next day and had some Goodyear Eagle F1 tyres fitted. They were 195/55/15, the correct size to maintain the rolling radius and the recommended handling tyre in "Modern engine tuning". I went for Goodyear Eagle F1s because a lot of people had recommended them to me and Protyre were doing a good deal on them. Total cost for four tyres fitted and wheels balanced was £220.

On the road I very quickly found out how much better these tyres were. The difference was astounding. Not only was the wet grip better, the behaviour of the car was that much better. It really brought a smile to my face. Imagine that you exited a roundabout a little too quickly in the wet, then the whole car would still point in the correct direction even though you could sense it slipping. I could only guess what traction would be like in the dry. It made me wonder what sort of 1/4 mile times I could achieve. Maybe I could shave a few tenths off my 16.1 best and finally get into the mid 15s?

One thing to beware of is that these cars eat front tyres. I have to change about every 4-5 months. That's about 15K of use. If you let them get too worn then they will let go in the wet!

When the front tyres are worn then I have the rear tyres moved to the front and new ones fitted on the back. I've stuck with Goodyear Eagle F1s throughout since they are so good.

First things first: the calliper slider arrangement used on the normal MK2 Astra and early GTE's is thorougly crap. Both Astra's that I've owned regularly warped the discs. This happens because the sliders seize up, the pads rub, the discs heat up. Hot wheels is the result. The symptons are a lot of rumbling noise, vibrations though the steering wheel and eventually very shaky braking. My 1.3 sounded like a train stopping.

The solution: at the front I fitted remanufactured brake calipers and packed the sliders out with Copper anti seize grease. Together with new discs this worked for a while.

Unfortunately the new discs warped after a few weeks. I thought that I had the answer to this common Astra problem. I had the discs ground true at Maynards a local engine machine shop. This cost £35. Unfortunately they also warped within a few weeks.

At this point I decided that more radical action was needed. I looked into the upgrades available. I discovered that the 16v Astra and the MK3 models had a better calliper design, called ATE. Apparently these do not warp discs so readily. So I decided to do the decent thing and fit them.

I was quoted £50 each exchange at local suppliers and engine shop Maynards. When I picked them up I couldn't see how they went together. After a visit to my local Vauxhall dealer and a look at the diagram I realised that I needed the main "carrier". Turns out that you can't buy them. So I bought two callipers from Cleave motor salvage for £47. Unfortunately, at the same time Maynards managed to get me some carriers for £20. So I ended up with two sets of carriers. Fitting the callipers was a simple job.

Once the new pads had bedded in (that means a day or so of weak brakes. There is a bedding in procedure that should be used, but I didn't know this at the time) the ATE calipers felt far superior. I could feel them bite and then come back off when taking my foot off the pedal. Very unlike the previous calipers, which although they could stop the car fine, were always rubbing or sticking a bit.

After a few weeks the new calipers really started working well. Much more positive than the previous ones. But the discs still warped. Someone told me that AP Lockheed had started to source their discs from China, and that a lot of problems with warping were apparent. So I looked around at what else was available. I bought some ATE Power discs from Online Autosport. They told me that they'd not had many problems with these warping. At £54 for the pair, they're cheaper than AP Lockheed ones. And I reasoned that ATE make the callipers, ATE can make the discs. When they arrived I was intrigued to see that they had a single groove in the surface that followed a "Celtic jewellery" pattern. Nice.

It was amazing to have smooth brakes again. After my first journey I checked the front wheels and they were a bit hot. So I pushed the car backwards and forwards for few minutes to dissipate the heat! After four days they hadn't warped and they seemed to work as well as the old ones. So things were looking up.

The discs lasted about four weeks before I warped them slightly during some enthusiastic use. Luckily they did seem to unwarp to a certain extent so they are liveable with. I am considering some more expensive ones in the future.

After a year or so the discs had worn a large amount. I replaced them with Vauxhall standard items. These did not warp either, but the braking didn't seem quite as good as it had been with the ATE discs.

I read recently that discs don't warp. What happens is that pad material is deposited unevenly on the surface of the disc. Material properties pay a large part in this.

I fitted braided brake hoses to improve pedal feel. I did the same thing to my last car. This is a pig of a job. Working on the rear ones is a neck ache special, the unions will probably be seized up, the clips that hold the joints to the bodywork are difficult to remove, brake fluid will leak out over everything and brake system bleeding is my least favourite job. I used a blow torch to cook the unions which worked very well. I bought a special brake nut spanner but it didn't fit, ended up using special adjusting graunching spanner (see here).

Despite all of the hassle, I do believe that it's a job worth doing if you want firmer brakes.

With the old callipers I had Ferrodo pads (£12 from Halfords). After a week or two of bedding in they provided very positive braking. That's when combined with new suspension components, a 40mm lower, and braided hoses. In the future I might try out some EBC Greenstuff or Mintex pads. Also Greenstuff or Black Diamond grooved discs.

The best pads I ever used came for free with the 16v calipers. They were astounding. I've never fouund

Fully braided hoses

When I had the car off the road for extensive chassis welding, I took the opportunity to replace all of the metal pipes with fully braided flexible hose. I obtained all of the bits for a very good price, some 2nd hand, some unused. No pictures at the moment.

Fitting the hoses was a fairly straightforward job. Various Banjo fittings and plugs were used to replace the four connections on the standard master cylinder with two active connections. One for the front brakes and one for the rear brakes. Two pipes were used for the front brakes. One pipe was used for the rear, together with a T piece at the rear of the car. Included in the set up was an in car adjustable rear bias control valve. This is a valve that restricts the amount of pressure in the rear circuit, so front-rear bias fine adjustments can be made.

At the time the pipes were not fixed down. Cable ties were used under the bonnet. The car failed the MOT for this, so I spent a few hours attaching plastic P clips inside the car and underneath at the rear.

I didn't really notice any difference in the braking performance after changing to braided hoses. However, they don't rust like standard pipes.

Adjustable Bias Pedal Box

The adjustable pedal box replaces the standard master cylinder with two master cylinders; one for the front brakes and one for the rear brakes. The input lever from the brake pedal pushes on a balance bar. This then pushes on the two master cylinders. By moving the connecting point on the balance bar it is possible to alter the force acting on one cylinder relative to the other. This allows the brake bias to be adjusted. A flexible shaft is often used to allow in car adjustment of the balance. Bias boxes are a common motor sport part. They do not generally come with vacuum brake servos though. Hence you have to press the pedal harder to lock up the wheels.