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      08-15-2016, 12:31 PM   #1
AriuSen
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So, I have done a extensive research on why people would track with the 18s, and mainly what I heard from people is because of bbk clearance and because tire companies dont provide 17" tires in 35 for their size.

This weekend I tried his 17x9.5 et 35 on my car and they clearly clear my bbk (PFC). I am not sure the size of my bbk, but it also clears my friends bbk (brembos)

Running 17s, will save me $200.00 per set!!! that is amazing!

Also, I would like to verify this information. running with 17x9.5 with 275/35/17, my gears will be shorter....I would be shifting fast which is a good thing!

Lastly look at the sheet I made....you can save 20lbs of UNSPRUNG weight.....that is a lot of weight to consider if you go with 255/40/17. Note that by going 255 compared to 275, the difference in width is very small. is 10.5 vs 10.8

So before I make the purchase, I would like to know from you guys....should I go with 275/35/17 or 255/40/17 ?

Advantage of going 255/40/17 is to save 20lbs of unsprung weight.
advantage of going 275/35/17 is to save only 8lbs of unsprung weight, but gears will be shorter (not sure this is true)

The HACK could maybe confirm?

Btw, if I go 275/35/17, I will have no issue with clearance as it will sit lower than my spring perch.

update: my friend told me, that by going 17 my speedometer will be off by 5%? I dont really actually care, as I dont really look at my speedometer at the track.
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Last edited by AriuSen; 08-15-2016 at 12:42 PM..
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      08-15-2016, 04:00 PM   #2
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Only laptime could tell. But I wouldn't be surprised if the 255 width 17" tires is faster than all the options available, especially if you're running stiffer springs/dampers.

The wider tires don't really give you more grip, it gives you more surface area to keep the tires cool. If you're not overwhelming your tires, running wider don't give you significant amount of grip advantage, ad as you've found, is detrimental in weight penalty. Especially for lighter cars.

The company that corner balanced my MZ4 Coupe, Tri-Point Engineering, was heavily into racing Miatas. They've found that in the 15" tire range, by going from a 225 to 245 width tire of the same compound, they actually LOST time.

Of course, a 2,200 lbs, 130hp on a good day car vs 3,1xx and 330hp...Different story. But I'm inclined to say that, if you've got the budget, test out all the different options available to you.

This also is dependent on your particular driving style too, and on which side of the grip you live on. If you tend to live on the right side of the grip curve, then wider tires will definitely help.
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      08-15-2016, 07:04 PM   #3
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Quote:
Originally Posted by The HACK View Post
Only laptime could tell. But I wouldn't be surprised if the 255 width 17" tires is faster than all the options available, especially if you're running stiffer springs/dampers.

The wider tires don't really give you more grip, it gives you more surface area to keep the tires cool. If you're not overwhelming your tires, running wider don't give you significant amount of grip advantage, ad as you've found, is detrimental in weight penalty. Especially for lighter cars.

The company that corner balanced my MZ4 Coupe, Tri-Point Engineering, was heavily into racing Miatas. They've found that in the 15" tire range, by going from a 225 to 245 width tire of the same compound, they actually LOST time.

Of course, a 2,200 lbs, 130hp on a good day car vs 3,1xx and 330hp...Different story. But I'm inclined to say that, if you've got the budget, test out all the different options available to you.

This also is dependent on your particular driving style too, and on which side of the grip you live on. If you tend to live on the right side of the grip curve, then wider tires will definitely help.

I think im gonna try the 255. the 275, i think will be harmful on slow turns.
Hope it works!
thanks will keep updated!
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      09-19-2016, 02:16 PM   #4
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Ok. I got updates now.
The weather this past weekend was the same compared to other days I was doing 1:58.2
I tried the new 17s in 255/40/17, and first lap.....1:56.8.
Is a major difference in corner exit and main straight speed. However in long sweepers, i noticed that 255 is not enough for our cars....they were also overheating too fast.
i wish maxxis had 265, but they only have 275/35/17.
I will keep using the 255/40/17 until corded, and then Ill see which one i will go for.
Super happy with the 17s. Car feels so much alive.
Btw, I did 1:56.8 in first session and then once it got 100 degrees, i was constantly doing 1:57s......17s is definitely faster
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      09-20-2016, 01:10 AM   #5
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Ah, trade-offs!

Are you still running the 650/750 lb springs? (I don't remember where that ended?)
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      09-20-2016, 09:41 AM   #6
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Quote:
Originally Posted by Finnegan
Ah, trade-offs!

Are you still running the 650/750 lb springs? (I don't remember where that ended?)
Right now I have 400 front and 550 rear haha
Went down a lot. And I feel like the car feels good with these rates + a front sway bar. Feels balanced now.
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      09-20-2016, 12:27 PM   #7
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Quote:
Originally Posted by AriuSen
Quote:
Originally Posted by Finnegan
Ah, trade-offs!

Are you still running the 650/750 lb springs? (I don't remember where that ended?)
Right now I have 400 front and 550 rear haha
Went down a lot. And I feel like the car feels good with these rates + a front sway bar. Feels balanced now.
Got it.
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      09-21-2016, 02:37 PM   #8
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Quote:
Originally Posted by AriuSen View Post
So, I have done a extensive research on why people would track with the 18s, and mainly what I heard from people is because of bbk clearance and because tire companies dont provide 17" tires in 35 for their size.

This weekend I tried his 17x9.5 et 35 on my car and they clearly clear my bbk (PFC). I am not sure the size of my bbk, but it also clears my friends bbk (brembos)

Running 17s, will save me $200.00 per set!!! that is amazing!

Also, I would like to verify this information. running with 17x9.5 with 275/35/17, my gears will be shorter....I would be shifting fast which is a good thing!

Lastly look at the sheet I made....you can save 20lbs of UNSPRUNG weight.....that is a lot of weight to consider if you go with 255/40/17. Note that by going 255 compared to 275, the difference in width is very small. is 10.5 vs 10.8

So before I make the purchase, I would like to know from you guys....should I go with 275/35/17 or 255/40/17 ?

Advantage of going 255/40/17 is to save 20lbs of unsprung weight.
advantage of going 275/35/17 is to save only 8lbs of unsprung weight, but gears will be shorter (not sure this is true)

The HACK could maybe confirm?

Btw, if I go 275/35/17, I will have no issue with clearance as it will sit lower than my spring perch.

update: my friend told me, that by going 17 my speedometer will be off by 5%? I dont really actually care, as I dont really look at my speedometer at the track.
If you ran 275/40/17 that would maintain the "correct" aspect ratio on the tire. The rule is when you go down one rim size you go up one sidewall size if width remains the same to keep as close to the right ratio as possible.
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      09-21-2016, 04:44 PM   #9
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^WHS
I'm certainly no expert, but I thought the object of going to a smaller wheel was to get more sidewall while maintaining the overall diameter.
Maybe I missed the point and the smaller wheel is a poor man's 4.10.
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      09-21-2016, 04:51 PM   #10
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Quote:
Originally Posted by Daemonblitz View Post
If you ran 275/40/17 that would maintain the "correct" aspect ratio on the tire. The rule is when you go down one rim size you go up one sidewall size if width remains the same to keep as close to the right ratio as possible.
Quote:
Originally Posted by StickMon View Post
^WHS
I'm certainly no expert, but I thought the object of going to a smaller wheel was to get more sidewall while maintaining the overall diameter.
Maybe I missed the point and the smaller wheel is a poor man's 4.10.
here is a video of how much faster im coming out of a corner + main straight.
the red m3e46 weights about the same as mine and with headers tune no carpet, racing seats, roll bar. he is a really good driver.

Last edited by AriuSen; 09-21-2016 at 05:38 PM..
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      09-21-2016, 04:58 PM   #11
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Wow! Setup sure seems to be working!!
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      09-21-2016, 09:28 PM   #12
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Quote:
Originally Posted by StickMon View Post


Wow! Setup sure seems to be working!!
+1
Great vid
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      09-21-2016, 10:10 PM   #13
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Oddly enough, i never heard about the lower center of gravity mentioned which might be the best aspect of running 17's and a smaller diameter tire. Regarding tire diameter, most guys i know run a smaller tire diameter than stock. Regarding width, as Hack has said, only consistent testing will answer that question.
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      09-30-2016, 07:43 PM   #14
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Quote:
Originally Posted by seank View Post
Oddly enough, i never heard about the lower center of gravity mentioned which might be the best aspect of running 17's and a smaller diameter tire. Regarding tire diameter, most guys i know run a smaller tire diameter than stock. Regarding width, as Hack has said, only consistent testing will answer that question.
You could probably lower the car about as much as the 17's would save you. On our cars I think a wider would help out quite a bit, m coupes aren't under powered like a miata may be when putting on a bigger tire. I can get near the end of traction on my M coupe pretty fast a little bit of extra grip would go a long way I think.

I wont get my car on the track till next year after some fresh tires and few things I want to do till I get it out there. I think swapping out for a 3.91 or 4.10 rear diff. may be the answer for a little extra acceleration and coming out of corners a little quicker. I think turner offers them as direct bolt ins.
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