Help AGAIN...tire size problem

2527 Views 10 Replies 4 Participants Last post by Canadian SRT8, Dec 12, 2011

SRT8ScoTT

Discussion Starter · Dec 12, 2011

Hi...now ive created a thread about tire sizes before and some how wont let me open it up so i just created new thread here!

basically i bought 255/45/20 tires for the back and didnt change the front 245/45/20 due to none in stock....now i know the outside diameter is wrong and it did cause odd noise coming from underneath the car so stopped driving!! BUT now ive been told that he wont be able to get 255/45/20 till the new year and i cannot wait that long!! ...saving grace (hopefully..thats what im trying to find out) he has some 265 and 275 options available ...i need help with the profile! my rim is a 9" ...whats my best bet to get outside diameter the same or ok so that it wont screw up my TC

Please need serious help with this
Thanks
Scott

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Startech

· #2 · Dec 12, 2011

Try this tire calculator to figure what will work. You want the diameter and circumference to be within 3%.
http://www.miata.net/garage/tirecalc.html

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Jeep Trick

· #3 · Dec 12, 2011 (Edited)

Most run a 275/40/20 on the 9" rim, if you are putting the same at all four corners it'll be fine

But if you are running a different width front to back, like stated you need to do the calculation to determine its within a safe differance

Edit: Looks like a 275/40/20 might be pretty close to your 255/45/20

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SRT8ScoTT

Discussion Starter · #4 · Dec 12, 2011

Spacelord said:
Try this tire calculator to figure what will work. You want the diameter and circumference to be within 3%.
http://www.miata.net/garage/tirecalc.html

first off thanks for this site! second, when you say 3% is that where it says "non-stock tire is x.x% too slow" ?? because when i put in my 245/45/20 - 255/45/20 (which ive at the moment) it says 1.2% ??? very confusing tbh as ive never really understood wheels tires etc;

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SRT8ScoTT

Discussion Starter · #5 · Dec 12, 2011

oh hang on...it says "too slow" for my current set up ...and for 255/45/20 - 275/40/20 "too fast" ....right i think im kinda getting it, so it must be within 3% "too fast" ?

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Jeep Trick

· #6 · Dec 12, 2011 (Edited)

SRT8ScoTT said:
oh hang on...it says "too slow" for my current set up ...and for 255/45/20 - 275/40/20 "too fast" ....right i think im kinda getting it, so it must be within 3% "too fast" ?

It gives you an actual measurement you have to do the math to determine if its less than 3%

Here is another one

http://www.discounttiredirect.com/direct/brochure/info/tmpInfoTireMath.jsp

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SRT8ScoTT

Discussion Starter · #7 · Dec 12, 2011

Jeep Trick said:
you have to do the math to determine if its less than 3%

HAHA ...ehm...any help with this one?!

i always mess up with percentages?!

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Jeep Trick

· #8 · Dec 12, 2011

Ill see if I can figure it out for you but I need to know what tire sizes you are thinking about using. Do you know what you have available to you? Also I would recommend keeping with the same brand if not the same model of tire if possible

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SRT8ScoTT

Discussion Starter · #9 · Dec 12, 2011

Jeep Trick said:
Ill see if I can figure it out for you but I need to know what tire sizes you are thinking about using. Do you know what you have available to you? Also I would recommend keeping with the same brand if not the same model of tire if possible

I do know he has 275/40/20 in stock and are the same tires! because i checked them out, so possibly them...as you said that looks like the closest....but if you able to calculate it for me and tell me what the best is....265/x/20 or 275/x/20

seriously much appreciated !!!