I have alloy wheels on my car but want to put normal steel wheels so my partner can practise dirving.

My car wheels have four studs and on the alloys it says 185/55 R15
firstly what do these numbers mean?

I had seen good cheap ones on the Internet (All four). This also has four studs and when I went to try on the wheels it did not fit. This was a waste of journey in terms of money and time.

How can I prevent this happening in future.

185/55 R15 is the tyre size (possible just recommended)…

185 is the width of the tyre in millimeters
55 is the height of the tyre sidewall as a percentage of the width. In this case 50% of 205mm. Also know as the aspect ratio.
R means Radial Construction.
15 in the diameter of the tyre's inner rim in inches.

Buying wheels to fit your vehicle is a bit of a black art, however the main considerations are…

1.) Bolt Pattern

This is known as PDC (pitch circle diameter) and often printed on the wheel, each wheel has a different bolt pattern, and some aftermarket wheels even have 2 different bolt patterns which allow them to be mounted on a wider range of vehicles.
The PDC is normally displayed as follows…
4x100
The "4" indicates the number of holes in the wheel for the bolts/studs on the cars hub.
The "100" indicates the diameter of the bolt/stud circle measured (normally but not always) in millimeters. Measurements are taken from the center of one bolt/stud hole to the center of the bolt hole directly across from it. Imagine a circle running through the centers of each bolt/stud hole.

2.) Offset

The offset of a wheel is the distance from the hub surface to the true centerline of the rim. A positive offset means the mounting surface is positioned in front of the true centerline of the rim. This in effect brings the wheel into the arch more. Conversely, a negative offset means the mounting surface of the wheel is behind the true centerline of the rim. This will cause the wheel to stick out.

3.) Centerbore/Spigot Ring size

Motor vehicle manufacturers use a central location collar on the hub in order to accurately locate the wheel. The wheel collar diameter or centerbore as it’s know, varies, depending on the make of vehicle. Some factory wheels have a centerbore that matches exactly with the hub to reduce vibration by keeping the wheel centered. Wheels with the correct centerbore to the car they will be mounted on are known as hubcentric. Hubcentric wheels take the stress off the bolts/studs & nuts. Thus its important that when selecting replacement wheels this is kept in mind.

Many aftermarket replacement alloy wheel manufacturers use an adapter (spigot ring) to vary the diameter of the locating hole. In this way, a particular wheel can, by changing the spigot ring, be used on a variety of vehicles.


4.) Backspacing

Backspacing is distance from the back edge of a wheel rim to the back of the center section. Measured in inches, backspacing is closely related to offset. This measurement is important because it determines the clearance of the wheel in the well, and the amount the wheel will stick out.

5.) Caliper clearance

Is just what it sounds like. The amount of clearance built into the wheel to allow for the vehicle’s brake disc and caliper assembly.

You don’t say the make and or model of your car however if it was available with steel wheels from the factory i.e. Alloys were just an option, that is what you need to source secondhand. My advise would be go to/contact a specialist breaker/dismantler/recycler for your make of car.
Failing that even when armed with the above information it may still be a bit of a suck-it and see exercise and may not completely be devoid of wasted time, however I hope this has helped and removed some of the mystery.
Best of luck and let us know how you get on.

thanks

that has been helpful