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Tyre load rating numbers

Posted: Mon Sep 18, 2006 1:24 pm
by Utemad
Hi guys.

Just wanting to know what the load rating numbers mean on tyres.

On our F250 the original tyres say 123/120R on a 265/75 16.

When I look up the specs of replacement tyres which at the moment are BF Goodrich KOs the 265/75 16 is rated at 120 with an S speed rating.

The tyre placard says the tyres should be LT265/75E and the axle weights are front 2241kg and rear 2817kg.

Do you just halve the axle loads above so front 1120.5 and rear 1408.5 per tyre? In which case the rear is slightly to heavy?

So how do I work out if the KOs have a high enough load rating?

When we replaced them last time we got Michelins and they have the 123/120R on the tyre also. We had a very limited range to choose from in that size when we replaced the original tyres last time due to the load ratings.

Posted: Mon Sep 18, 2006 1:49 pm
by -Scott-
The state transport authority in whatever state you're in will ultimately look at manufacturer's recommendations, typically found in the owner's manual and/or on the tyre placard. That sets the minimum tyre load rating for the vehicle - I'm surprised there's no load rating on your tyre placard.

I'd also suggest the axle weights are absolute maximum ratings - does an F250 have a GVM over 5 tonnes? :?

The dual number is for single/dual application - your current tyres have a 123 load rating when you have one tyre per corner, or 120 if you run duals (on the rear?)

Personally, I'd try the manufacturer or state authorities to get something in writing BEFORE buying new tyres.

Good luck,

Scott

Posted: Mon Sep 18, 2006 2:23 pm
by Utemad
Going by the BF Goodrich website a 120 is 1400kg and a 121 is 1450kg. So a 121 should be high enough. Pity their 265/75 16 is a 120.

The owners manual says 4173kg GVM with a 2760kg Maximum Gross Rear Axle Mass. In which case the rear axle would be 1380kg per tyre so under the 1400kg of a 120 tyre.

I'll ring Ford. This is just weird.

Posted: Mon Sep 18, 2006 3:40 pm
by RoldIT
Why don't you try a 285/75R16?

They are usually a slighty higher load rating than the 265. Only a few mm larger and would fill the wheel arches on those big bastards a hell of a lot better than the OE size.

Plus, with the big diesel, you'll never even notice the small difference in gearing.

Posted: Mon Sep 18, 2006 3:50 pm
by Utemad
RoldIT wrote:Why don't you try a 285/75R16?
I'd love too :D

However it is a work ute and the 285s are 32mm larger which is more than Qld DoT will allow. You also need an 8in rim and we have the stock 7in mags. Not keen on changing rims.

Posted: Mon Sep 18, 2006 4:00 pm
by RoldIT
Utemad wrote:
RoldIT wrote:Why don't you try a 285/75R16?
I'd love too :D

However it is a work ute and the 285s are 32mm larger which is more than Qld DoT will allow. You also need an 8in rim and we have the stock 7in mags. Not keen on changing rims.
Fair enough, wasn't aware they were only 7" wide rims.

Anyway, Toyo are just about to release these new treads to AUS. Think I'll give em a try when my roadies run out ...

LT265/75R16 123P

http://www.toyo.com.au/RVPDFs/OP%20MT.pdf

Posted: Mon Sep 18, 2006 4:22 pm
by Utemad
The rims are 16x7. The tyre place did tell us our options would open up if we had 16x8 rims.

The standard size tyres do look like skateboard wheels under the F250. It needs some 35s just to look normal :cool:

I'll keep the Toyos in mind. They have the right load rating.