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Old 02-18-2010, 03:50 AM   #1
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Default 15in tire fitment question.

Here is the situation that I am facing. I don't want to shread my new street tires (Yokohama s-drives) while driving on track. I sold my Spec Miata to get my current miata. Sold the rims but kept the almost brand new RA1's (2 track days 10 20 min sessions). They are 205/50r15. I would like to run 225/50r15RA1's later down the line. I am not racing but will be doing TT with NASA. My TT class limits me to 225 without points at this time. Still not boosted as of yet so I am in TTE at this time.

So my research shows that the 205 max rim is a 7.5in. The 225 max rim is a 8in. This is from Toyo's site.

I am going to be at Cal Speedway next month and won't have the money for the wheels and tires. I don't want to stretch the 205 tires too wide but yet don't want to get a rim that won't be wide enough for the 225 tire. I am not looking to get the absoulute lightest wheel but not looking for a heavy one either.

I have found a 15x7.5 at good-win at 14lbs. I would love to get an 8in wheel for later down the line though.

So for my question will the 8in wheel be too wide for the 205 RA1's that I have. I am shure they will fit but will it be dangerously too wide. If so will the 7.5in wheel be a good fit for the 225 RA1's when I get them.

If this setup would not work I would be oppen to offers.

Have a great day,
Jared
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Old 02-18-2010, 09:17 AM   #2
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You will get a better contact patch for the 225 with the 8" wide wheel. You can however surely fit that tire comfortably on a wheel size that won't stretch your 205 .

My last setup was the Kumho Ecsta SPT in a 215 section, right between your two options. It fit on a 6.5" wheel, almost square. I didn't feel it was the best contact patch, but still very predictable. Some of that may be due to how awesome that tire was, but the point is that 10mm (~13/36") will not have a problem fitting a wheel a full inch wider.

Common knowledge amongst the track guys here though is that wider wheels are faster. Period. This would mean making a compromise in your wheels now just to run some used tires, when you know you are upgrading later. I would think long run in this situation.

6ULs?
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Old 02-18-2010, 11:26 AM   #3
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I agree 100% with you about the later coment. That is what I am thinking. I would like to go with the 8" rim, but cant afford the new tires at this time. Crappy place to be.

6ul's would be great but that would just delay the tire even longer. Just a bit more money. Great rim though.

I think ou have confirmed my thoughts and fealings about this.

Have a great day,
Jared
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Old 02-18-2010, 11:49 AM   #4
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225's will fit on a 15*7 just fine dont worry about it man
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Old 02-18-2010, 12:18 PM   #5
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So a 7.5 would be ok for both tires correct. I would like maximize the 225. I know that the 8" would be ideal but cn't believe that the 7.5 is going to be that dramatic of a differance in the handeling. I may be wrong. If I don't get any hits on my tires then I may just go with the 7.5's.

Have a great day,
Jared
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Old 02-18-2010, 12:32 PM   #6
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Dude, just buy the 8"s...I mean the 205/50s aren't really going to be a stretch on that anyhow...at least not in the cr.net sense of the word. Just be easy to curb, but allow you to use our current set in the meantime, and provide predictable breakaway with both tire sizes.

I'm not sure how much difference 0.5" makes, but everyone talks about how much better (faster) the 9" is over 8".

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Old 02-18-2010, 01:45 PM   #7
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7.5 is just fine man if you put a 205 on a 8 incher you could have air pressure problems just buy the 7.5's and be done with it.
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Old 02-18-2010, 01:47 PM   #8
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Quote:
Originally Posted by Jfornachon View Post
Here is the situation that I am facing. I don't want to shread my new street tires (Yokohama s-drives) while driving on track. I sold my Spec Miata to get my current miata. Sold the rims but kept the almost brand new RA1's (2 track days 10 20 min sessions). They are 205/50r15. I would like to run 225/50r15RA1's later down the line. I am not racing but will be doing TT with NASA. My TT class limits me to 225 without points at this time. Still not boosted as of yet so I am in TTE at this time.

So my research shows that the 205 max rim is a 7.5in. The 225 max rim is a 8in. This is from Toyo's site.

I am going to be at Cal Speedway next month and won't have the money for the wheels and tires. I don't want to stretch the 205 tires too wide but yet don't want to get a rim that won't be wide enough for the 225 tire. I am not looking to get the absoulute lightest wheel but not looking for a heavy one either.

I have found a 15x7.5 at good-win at 14lbs. I would love to get an 8in wheel for later down the line though.

So for my question will the 8in wheel be too wide for the 205 RA1's that I have. I am shure they will fit but will it be dangerously too wide. If so will the 7.5in wheel be a good fit for the 225 RA1's when I get them.

If this setup would not work I would be oppen to offers.

Have a great day,
Jared
First of all ignore the Lawyer talk from Toyo for the specified rim widths. It was tough for me to do at first as well. But what you will find is the Toyo 205’s will work best mounted on an 8” rim and the 225’s will work best mounted on a 9” rim. Also maximizing wheel width will lower lap times more than saving a few pounds of wheel weight.

They will look tad stretched? yes but not Club Roadster like stretched those guys are like putting 185's on 10" wheels.

Bob
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Old 02-18-2010, 05:49 PM   #9
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Bob- Thank you for your reply on the mounting of the 205's on the 8" wheel. If the buyer passes on the 205's I will just end up holding on to the tires and use them up and then get the 255's.

I don't mind takeing chances hence me going out to the track I just don't want to got to big and hit a bump and blow the tire out and crash because I took the chance and went to wide because I didn't look for someone elses experiance.

Have a gret day,
Jared
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