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I Solve Problems
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Am I missing something?

if the diameters are equal, how is the circumference different?

ok, this is a very tire dependent issue it appears.

the AD07 in 25.3" has 820 revs per mile 235/40 18 and 265/35 18 which makes sense, due to the fact that they have the same diameter.

how a tire of 25" can some how turn 100 more times than another tire at 25" boggles me.

now if the 25" diameter was measured before it was mounted on the wheel, then mounted on the wheel and the tire is "stretched" on the measured rim then ran for a mile and recorded it would indeed be a smaller diamter than if the tire wasn't stretched.

tell me I'm missing something obvious and this has just been a long day.
 

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the fact of a tire being "pinched" or stretched to the point of significantly changing the overall diameter could push an otherwise "mathmatically sound" un mounted tire combo past the 2 or 3% difference range.

maybe it has been a long day....
 

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T3h_Clap said:
tell me I'm missing something obvious and this has just been a long day.
Your missing something obvious and it has just been a long day. <hell i don't know>
 

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dailydriversti said:
Your missing something obvious and it has just been a long day. <hell i don't know>

haha :lol:

<twenty eight PM's later>

<haha this isht doesn't work if you use numbers>
 

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jph said:
<s>i beg to differ.</s>

EDIT: nevermind... it looks like i based my calculations on a typo ;)

ps: IIRC SOA wants all tires to be within 2% of each other. so 225/45R17 and 245/40R17 should be within spec.
but you're right, a 255/40R17 would be a better match ;)


J.
your #s were pulled right off tire rack.

I checked, your #s were what they say they are.

I knew i shoulda quoted you!

this topic is still on the table!! why the hell?! are they different Revs per mile?
 

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T3h_Clap said:
your #s were pulled right off tire rack.
yes. there must be something wrong with the numbers they have for the ps2 in 255/40r17 on tirerack.
when i check different brands or types, they all showed 225/45r17 and 255/40r17 to be almost the same. it can't be that for this one particular tire (that i happened to pick for my example! :banghead: ) it's any different ;) must be a typo on the tirerack site.

sorry for the confusion, i removed all my speculation ;)


J.
 

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a tire stated to be 255 doesn't have to really be 255 on a given wheel width.

I'm truely interested in this, this needs to be added to my "t3h_spreadsheet"
 

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jph said:
<s>i beg to differ.</s>

EDIT: nevermind... it looks like i based my calculations on a typo ;)

ps: IIRC SOA wants all tires to be within 2% of each other. so 225/45R17 and 245/40R17 should be within spec.
but you're right, a 255/40R17 would be a better match ;)


J.
If you ran the 245/40R17 as front tires, they would still wear more rapidly than the 225/45R17's in the back. This means that the difference in diameter would become larger through the life of the tires.

Then again, this idea of different front and rear tire sizes is probably something that 99.98% of us will not try. It is very difficult to get right and the benefits of a setup like this are questionable. You can increase the amount of front grip using suspension changes without taking away your ability to rotate your tires. :)
 

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agreed, rotating race tires is good on the budget.
 

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I can't believe that no one has mentioned you will DAMAGE YOUR TRANSMISSION if all 4 of your wheels are not the same.

If you're having handling issues, there are ways to fix it, but putting different tires on the front/rear will accomplish nothing.
 

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Ver7wannabe said:
The closest I have seen done like that was on an EVOs built by some Japanese tuning houses. They do the opposite though and put narrower RIMS(not tires) on the BACK of the car to try an get more oversteer out of the car.

As far as staggered width tires on any AWD car, you must make sure that they have the same diameter on all four corners or else your diffs will be very unhappy and can fail.
+1 on that :D
 

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Jag32 said:
I can't believe that no one has mentioned you will DAMAGE YOUR TRANSMISSION if all 4 of your wheels are not the same.

If you're having handling issues, there are ways to fix it, but putting different tires on the front/rear will accomplish nothing.
I did :D

Ver7wannabe on page 1 said:
As far as staggered width tires on any AWD car, you must make sure that they have the same diameter on all four corners or else your diffs will be very unhappy and can fail.
 

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Ver7wannabe said:
Jag32 said:
I can't believe that no one has mentioned you will DAMAGE YOUR TRANSMISSION if all 4 of your wheels are not the same.
If you're having handling issues, there are ways to fix it, but putting different tires on the front/rear will accomplish nothing.I did :D
I was implying this as well (as i'm sure others were, hence trying to talk him into same sized tires), read the thread before making assumptions.
 

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Jag32 said:
I can't believe that no one has mentioned you will DAMAGE YOUR TRANSMISSION if all 4 of your wheels are not the same.

If you're having handling issues, there are ways to fix it, but putting different tires on the front/rear will accomplish nothing.
I CAN"T BELIEVE you said that!?

do we all need to repeat the obvious 500 times?

and no all 4 wheels do not need to be the same! they need to have near identical roll out between all four wheels when mounted on the desired wheels.

a tires sectionwidth therefore aspect ratio can change very easily based on the wheels chosen. so even with using the same tire on 4 wheels you have have issues depending on wheel width.
 

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<s>i beg to differ.</s>

EDIT: nevermind... it looks like i based my calculations on a typo ;)

ps: IIRC SOA wants all tires to be within 2% of each other. so 225/45R17 and 245/40R17 should be within spec.
but you're right, a 255/40R17 would be a better match ;)


J.
Hello I was hoping you can help me. I have a 2018 Subaru wrx. Would 245/40/R18 and 275/40/R18 work? Plz help thank you
 

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The only way to make this work in the long run is having the same tire diameter, front to rear. The two tire sizes above do not fit this category.
 

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What J said.
 
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