Mazda MX-5 - Tyre Information

A close inspection of the wall of most quality tyres will reveal a number of interesting markings.

Apart from the brand and country of manufacture details, there is information on size, load, speed, wet road braking, temperature ratings and wear index too.

Tyre Size.

This table shows the original specifications for tyres on Australian MX-5's (Excluding special editions)

Model and OE Tyre Specification	Tyre Width	Sidewall Profile	Rim Size	Speed and Load Rating	UTQG	Came with
NA6A 1.6 (Aug 1989 - Sept 1993) 185/60 R14 82H	185mm	60% of 185 = 111 mm	14 inch	H = 210 Kph 82 = 475 kg	Not Available	Bridgestone SF-325 (mostly)
NA8A 1.8 litre (Sept 1993 - Jan 1998) 195/55 R14	185mm	60% of 185 = 111 mm	14 inch	H = 210 Kph 82 = 475 kg	Not Available	Bridgestone SF-325 (mostly)
NB8A (Jan 1998 Nov 2000) 195/50 V R15	195mm	50% of 195 = 97.5 mm	15 inch	V = 240 Kph 82 = 475 kg	180 A A	195/50/15 Michelin Pilot SX
NB8B (Nov 2000 to ??) 205/45 R16 83W	205mm	45% of 205 = 92.25mm	16 inch	W = 270 Kph 83 = 487 kg	140 A A	Bridgestone Turanza ER30

Interpreting the tyre codes

The tyre size coding is a mix of metric, imperial and ratios values.

For example, my Yokohama AVS ES100 tyres carry the following data

205/45/ R16 83W …. this means

· 205 = width of tyre at its widest part (excluding raised lettering) in mm.

· 45 = the aspect ratio for the relationship of sidewall height to width (45% of 205mm = 92.25mm)

· R = Radial construction for road use

· 16 = rim size in inches.

· 83 = is a code for the load capacity of the tyre. 83= 487kg (this gives a theoretical maximum load of 1948kg (487 X 4)

· W= is the code for a speed rating of 270kph

Uniform Tire Quality Grade (UTQG) (An American Standard which is almost globally adopted)

The AVS ES100's are branded 280 AA A

· 280 = Treadwear

· AA = Traction in terms of straight ahead wet road braking (this is not a cornering or dry weather rating)

· A = Temperature resistance to the heat generated by running at high speed.

Additional Information

1. Speed Ratings

The speed rating applies to pristine condition tyres run at the correct inflation and on suitable weight cars. It is the maximum speed to which the tyre is rated.

N=140km/h	P=150km/h	Q=160km/h	R= 170km/h
S=180km/h	T=190km/h	U= 200km/h	H= 210km/h
V= 240km/h	Z= 240km/h plus	W= 270km/h	Y= 300km/h

Source Tirerack.com

2. Treadwear

Treadwear values are relative and are a guide to the wear rate of tyres given identical driving conditions and habits. A treadwear rating of 280 (Yokohama AVS ES100) should wear at half the rate of a 140 (Bridgestone Turanza ER30). Racing tyres have treadwear ratios around the 40 mark.

3. Traction

A tyre's rating in straight-line wet braking traction is graded A, B, or C (A being the best traction). Changing tyre technology resulted in AA ratings being introduced in 1997. Tyres registered after 1997 can carry the AA rating. It may be that pre-1997 registered tyres with an A rating are AA equivalent as the standard was not backdated. Traction grades do not indicate dry condition or wet cornering qualities of a tyre.

4. Temperature

A tyre's resistance to the heat generated by running at high speed Temperature resistance is graded A, B or C. A is the highest grading, C is the minimum level of heat resistance for passenger cars.

Safe Journey

Rob (Techno) Spargo

Mazda MX-5 Club Victoria