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Discussion Starter #1
my new tires have a load index of 88
kumho 711 (same rating as the 712)

means a weight of 1234lbs
reccomended 91 in the other thread means 1356lbs


am i in danger?

what if any are the potential risks/hazards?
 

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Yes. You should not be driving on those.

Risks? Immediate blow out possibility.
 

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how do we know it has to be 91 minimum?
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If you search the board and read the Wheel/tire FAQ there is tons of information about how our cars need atleast 91 Load Index. Anything under isn't designed to handle the weight of the car.

My Kumho Supra 712's have a 92 load index, so I don't know who told you that they had 88 also...

You can double check here if you would like : Supra details for 225/40/18
 

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Better replace all your body panels with carbon fiber, get some Gram Lights, titanium exhaust, Lexan windows and move the battery to the trunk. That'll help. :D

Seriously, there's a good risk of blowout with an 88 rating, I'd tell the person that sold those to you to take em back as they've made the car unsafe to drive and replace them with a tire with the proper load rating.
 

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Discussion Starter #8
its gonna be a hassle and a half to get them changed from this guy.

its only a difference of 121 lbs spread over 4 tires i think i'll be ok

if i die, you guys can chime in and say "i told you so"

:)
 

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its gonna be a hassle and a half to get them changed from this guy.

its only a difference of 121 lbs spread over 4 tires i think i'll be ok

if i die, you guys can chime in and say "i told you so"

:)
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That's 121 lbs on each tire. You may seriously want to consider replacing these tires.
 

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its gonna be a hassle and a half to get them changed from this guy.
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If you're stuck with them, then at the MINIMUM, keep the tires inflated to the max, which should be 36 psi for that size. Try not to load your car too heavily for long periods of time. That should help prevent any catastrophic failures.
 

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yeah in all seriousness, keep the car as light as you can. you might want to be a bit more careful about speedbumps and potholes as well.

what size did you get? 205/45/17?
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He has another post about his wheels/tires.... He is running a 225/40/18... So his psi should be even higher then 36...
 

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its gonna be a hassle and a half to get them changed from this guy.

its only a difference of 121 lbs spread over 4 tires i think i'll be ok

if i die, you guys can chime in and say "i told you so"

:)
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Why even bother asking for information if you are just going to say it is a pain to bother with? :goon:

I think it will be more of a pain if the tires do fail and insurance company finds out they are inadequate and deny your claim. What if you or your passenger are seriously hurt? Still too much of a bother?
 

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He is running a 225/40/18... So his psi should be even higher then 36...
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Standard load tires max out at 36 psi (that's the 88 load index he's referring to). Some say 44 psi on the sidewall, but you don't get any additional load capacity above 36. If his tires allow 44, then he should put 38-44. Reinforced tires go up to 50 psi and will gain additional load capacity all the way up to 50. A reinforced load 225/40R18 would be 92 load index.
 

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these say max psi 50
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That's odd. In any case, you'll need to keep them inflated at or above 36 psi. Don't expect a lot of treadlife out of those, and next time make certain your tires have the proper load index. We don't want to see you getting hurt. :)
 

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Discussion Starter #18
thanks guys, i dont want to sound unnapreciative or anything, next time for sure i'll check into this before getting tires.
 

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i'll join the 88W club... my new Yoko's are 88W as well and also say max psi of 50lbs...

which, by the way, is bullshit on the part of wheelmax for not having a load rating chart showing the minimums for a given vehicle...

but you know i checked that shit before ordering and even yoko's site gives my size (225 40 18) a 91W rating...

who knows...
 

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its gonna be a hassle and a half to get them changed from this guy.

its only a difference of 121 lbs spread over 4 tires i think i'll be ok

if i die, you guys can chime in and say "i told you so"

:)
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In the US:

Mazda only spec's 91 load rating for 16" tires on the 6i. For 17" and 18", the load rating spec is 93.

Load tables ( 88, 91, 93 ..) are based on 35 psi for most standard (sl) tires, and 41 psi for xl tires. If your pressure is less than these values, reduce the load rating by about 20 lbs per psi.

Load spec is based on front GVWR, which includes load dynamics and is 2361 lbs (both i and s). It is suggested that you go 10% over, so the design load per front wheel is 1298 lbs.

The 16" 91 tires, at mazda's 32 psi, have a net 1296 lb rating.
The 17" 93 tires, at 32 psi, net out at 1373 lbs.
The 18" 93 tires, at mazda's 35 psi, rate at 1433 lbs.

Any standard 88 tire rates at 1235 lbs at 35 psi.

So although you are just 63 lbs underrated per tire with your 88's based on GVWR, you are about 200 lbs below Mazda's spec for 18" tires.

But join the club. Mazda used 93-xl 17" michelin's on the mazda6, and said use 32 psi. That downgrades the 93 rating at 41 psi to 1253 lbs at 32 psi. Don't know if they used xl's for the 18" wheels.

So you are well below Mazda's suggested capacity rating of 1433 lbs for 18" tires, and increasing pressure will not increase capacity on SL type tires.

I'd still just bump them up to 36-37 psi, and not do high speed track events.
 
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