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Discussion Starter · #1 ·
Hi All,

I have 8" X 18" front wheel and 9.5" X 18" rear wheel setup, that I use only for AutoX

My questions:

Can I use Yokohama 245/40R18 front and 275/40R18 rear?

I am not worried about the rear as I am already running 275, but the current fronts are 235 and Tirerack doesn't have 235 /40R18 for the front anymore so I have to consider 245/40R18.

So I would like to check if someone is running the setup and can vouch that it fits and does not create any issues

Also open to ideas on other brands for autocrossing.

thanks in advance...
 

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If you used 255/40/18 f and 275/40/18 rear, you will notice almost no understeer However if you can not find a tire shop that can install the 255/40/18 in front due to a 8" wheel, then 245 certainly will work. Are these OEM wheels with a 57 offset in f and 43 offset in the rear?
 

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Discussion Starter · #3 ·
If you used 255/40/18 f and 275/40/18 rear, you will notice almost no understeer However if you can not find a tire shop that can install the 255/40/18 in front due to a 8" wheel, then 245 certainly will work. Are these OEM wheels with a 57 offset in f and 43 offset in the rear?
Thanks Apex

front has 57 offset and rears have 49 offset

so front reads

8J X 18 H2 ET 57
Shoe Automotive tire Automotive design Automotive lighting Tread

rear reads
9.5J X 18 H2 ET 49

Wheel Automotive tire White Alloy wheel Tread
 

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Your tires will be too big for your wheel widths, This causes unwanted tire squirm and promotes lateral rotation around the rim. Hardly anyone thinks about this on this forum, but it is the first thing they should think about, not more tire patch. Ask a pro racer, not someone who sells tires.
 

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Discussion Starter · #5 ·
Your tires will be too big for your wheel widths, This causes unwanted tire squirm and promotes lateral rotation around the rim. Hardly anyone thinks about this on this forum, but it is the first thing they should think about, not more tire patch. Ask a pro racer, not someone who sells tires.
thanks a very valid point and good you brought it up for discussion

I asked the person who won the PCA New jersey region championship and she said she ran even 265's in front without issues and 245s have a plenty of room to spare.

Reason i asked her was:
1. I bought these wheels from her
2. she was driving the same car as mine so there is some comfort in that :)

Also i think even thought the width is more but the aspect ratio is 40 instead of 45 there is still plenty of room

i am checking with her about the spacers
 

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I have been doing a lot of research into possible replacement tires for the nearly worn-out dealer provided Michelin PS4S on my car and I noticed that the tire manufacturers have rim width fitments specified for a particular size tire on their websites.
 

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Discussion Starter · #7 ·
I have been doing a lot of research into possible replacement tires for the nearly worn-out dealer provided Michelin PS4S on my car and I noticed that the tire manufacturers have rim width fitments specified for a particular size tire on their websites.
except for yokohama they tend to tell you 235 / 265 but that is not available on tirerack

just spoke with tirerack guy he says 245 fits 8" wide wheels
 

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I have been doing a lot of research into possible replacement tires for the nearly worn-out dealer provided Michelin PS4S on my car and I noticed that the tire manufacturers have rim width fitments specified for a particular size tire on their websites.
A range of wheel widths will work with a given spec, but my point is only relevant for drivers who can drive to 9/10s or 10/10s on track and want optimum adhesion. Also, a narrower tire will heat up more quickly, have less unsprung weight and less aero drag.
 

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Discussion Starter · #10 ·
well no use tire rack has only 1 tire left of A052 for rear

I am going to go with Nankang CR-S a.k.a CR-1

245/40ZR18 and 275/40ZR18

from my sources they are cheaper / last longer and comparable in performance fingers crossed
 

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How did it go?

I got the same 245/40/18 and 275/40/18 Advan Apex V601 tires for my stock 18" wheels.
Checking from tire size calculator, these sizes have comparable circumference reductions vs stock (-2.3% front, -2.6% rear)
Will have to get them mounted.

Sick of paying stupid prices for standard sizes & inferior tire choices.
 

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Discussion Starter · #12 ·
How did it go?

I got the same 245/40/18 and 275/40/18 Advan Apex V601 tires for my stock 18" wheels.
Checking from tire size calculator, these sizes have comparable circumference reductions vs stock (-2.3% front, -2.6% rear)
Will have to get them mounted.

Sick of paying stupid prices for standard sizes & inferior tire choices.
I agree, looks like there is a shortage of tires of some sort hence getting right tires is as difficult as finding the right line :)

On stupid prices - mount and balance + alignment in a local shop is 800 another shop 400 ... this another shop is very trusted by many of my autox friends and such places are a rare find
 
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