Help with Tyre Jargon Please!

I think a lot of this confusion stems back from the 1970's. You see, what happened was, is that all of the tyre fitters back then had about the same status as say, a chimney sweep.

They all got together, and decreed that they would elevate themselves in the workforce hierarchy, and they adopted a cunning plan. What they did was basically invent their own secret code, which is like tyre changing 101 meets the Free Mason's secret handshake.

So, almost overnight, you average Joe Blow blue shorts & singlet tyre changing dude, was suddenly.......... well............ just full of new fandangled tyre speak. This was a good thing at first. Hubby would send his wife down to the Tyre Mart, and she would be bamboozled by the Gobbledygook tyre speak, and a lot of women fell for this, like these dudes were almost like men in uniform!

Wife would then go home, and tell hubby that she had some 250R/75/15/Magnums put on, and the husband, not to be outdone by a tyre monkey, would then invent his own code........."Well, Darling, if I was him, I would have put 260/2567FT/16/5's on the front, at 36 psi, & 765/XXX/17 on the rear at 200 kpa!" This little rebuttal would have made him look all good again.............

So, as time went on, the numbers became blurred, and it simply became a p1ssing competition. As time evolved, some of the mud stuck, and we still know the numbers today. Just pretend you understand the secret code, or bow to the Tyre God, and humbly say..........."I want those black round ones please...."

Sorry, just can't help myself somedays...........

Wolfie

255 is the width
70 refers to aspect ratio ( profile is 70% of width)
R refers to the tyre rating
15 is the rim diam.

30 refers to the standing height of the tyre in inches.
9.5 is the width in inches instead of cm
R refers to the tyre rating
15 is the rim diam.
LT refers to the tyre type (light truck for instance)

You will pay twice the price buying the 255. Which incidently is a 10 inch tyre. 30X10X15 's are as common as mud and cheap as chips go for this size and save dollars and enjoy the choices available.

How ya going

255/70R15=
255 section width in mm or width of tred
70= Aspect ratio or hight of tyre
R= tyre constructon in this case radial
15= Rim diameter in inches

30*9.5r15LT is a bit smaller then your current 255/70R/15 the closest is 31/10.5R15 which r just a bit bigger say 265/75R15 i think. That will put your speedo out by about 3km no biggy. The LT in all this stands for Light Truck construction which is a must for bush driving make sure you get a 6to10 ply construction

hear r some aprox cost's for u
BFG AT 31/10.5R15LT $258
cooper AT 31/10.5R15LT $229
ST " " " $243
cooper at 30/9.5R15LT $218
Bridgestone AT 3110.5R15LT $220
Goodyear At 31/10.5R15LT $186

All tyre retailers have a chart that converts from one to the other. Check it out.

google gold

tyre calculator

Melly
Most SR5's need to have a load carring index of 112 and most 31x10.50r15 have only got an index of 109 so therefor not legal fitment.You can fit a 265/70r15 some have 112 index which l think is much better size and a few more available.

Ok...so now after my crash course in tyres we have a few options...not really the options we were after but still its not all bad. All these have the correct load rating of 112 or over.

Cooper AT's or ATR's 265/70R15
Goodyear Wrangler ATR's 265/70R15
Bridgestone Dueler AT D691 255/70R15 *The only tyre with the EXACT specs
Michelin LTX AT's LT265/70R15

None of the 30x10.5R15's nor the 30x9.5R15's had a load rating over 112....mostly were 104 or 109. No muddies :(

I bet there are a hell of a lot of SR5 owners out there driving with illegal tyres, we don't want to risk the insurance company telling us they aren't covered in the case of an accident or some other misfortune.

Now im gonna go and apply for a job at Beuarepairs or Bob Jane.

Thanks again for all the responses.

Just so that those out there are aware....

The rear axle load rating on the SR5 Hilux is 1570kg (front 1180kg).
According to the vehicles placard:-

"The sum of the load carrying capacities of tyres fitted to any axle or axle group of this vehicle shall not be less than the relevant load shown above."

This basically means that a load rating of 100 (785kg per tyre) is completely legal and insurance shouldn't have a problem with this. For this reason the 30x9.50R15 with 104 load rating is fine... the 31x10.50R15 109 load rating is fine aswell, just the overall diameter is too big...legally.
I work in a company that supplies after market tyres to Toyota for their Hilux SR5 and fit 30x9.50R15 104Q with no dramas at all.
If you would like some more info : ryano@fourbys.com.au
Cheers,
Ryano

google is your friend, theres a trillion websites explaining these differences. also tire calculators to convert sizes.