Choosing the best tyre/rim combo is both an art and a science - let us put our combined know-how down in this thread for the benefit of all. Just keep adding 8)

Firstly, what things are called and how they are measured:

The 'wheel' is the complete set made up of two parts: the 'rim' is the metal part where the bolts go on, and the 'tyre' or 'tire' is the rubber part.

Funnily enough, this means there is no 'spare tyre' except around your waist - it's a 'spare wheel'

They are measured as follows:

TYRE:


185 is tyre width in mm, so that tyre sits on the ground measuring 18.5cm across. When we deflate, it will go out to maybe 22-24cm - for sand we want the widest possible that will fit in the wheel well without rubbing.

185mm is an economy car tyre width - we're looking at 265-315 width...

60 is the aspect ratio which is the height of the rubber from the ground to the rim edge, and here things get a little stupid - it's not 60mm as any normal human being would think - it is 60% of the tyre width... so, 60% of 185.

That would be a section height of 111mm:


For off-roading, we want that number as high as possible, until it starts rubbing against the car fender, so 60-80. For speed on tarmac, we want the opposite, 45-55, and they are called low-profile tyres, like in the pic above.

The last number after the R (for radial, steel-belted tyres) is 14, and this is the diameter of the metal rim in inches... for a good choice of off-roading tyres 15 or 16" rims are ideal.

Next, I'll add how rims are measured.

Sounds good ....waiting for the next instalment !:smiley2::smiley8:

very educational, keep going...

I'll keep going LOL but you guys need to add, too!

One of the very special things about a club such as uaeoffroaders is the combined experience and knowledge of the members - if you think about it, we are specialists in this area, and the value of our combined know-how is immense!

here is a good table outlining what gear ratio best matches what tire size based on either fuel economy, stock performance or more power. This is from the JEEP forum, but is a good base for any tire upgrade.

LOL..Tony the tire sizes are in inches .....we don't do inches here in the UAE

No worries, here is a tire size converter: http://www.onlineconversion.com/tire_si ... ersion.htm

In the above chart, you'll notice the sizes down the left column are expressed as the diameter of the entire tyre in inches, which is an American system different from the international 185/60R14 system.

For our purposes, we'd be looking at sizes 30" to 33"... and maybe some 35" 8)

Is that so, my tires must be imposters then eh!
Thanks PR, forgot to add the calculator.

Wasif Ahmed wrote:LOL..Tony the tire sizes are in inches .....we don't do inches here in the UAE

Nice over view of the basics although a metric tire's number are all in "mm" and not "cm" but I followed ya.

Ur too funny WA, there is no tire measurement standard in the UAE.

If one is looking at a gear swap do to tire size change or to try and recover the lost power from said, it is best to search the web for info specific to you car and transmission. There are two charts just for the Jeep JK, one for the Manual and the other for the Automatic. There are significant differences between the two systems that most gear heads are aware of but your average Joe may not be.

Ah, thanks for the clarification Eric. So this must be simply for ZJ's then. Ah well, not to worry, there are a few of us here and there!