Autocross tires

[eng90]

I have a 2013 boss, it has the oem mt82 and 3.73.. and would like to know whats best size to get for my oem 9 inch front wheels and 9.5 rear ?

I will be going for pss ... and donno if i go for same 255/40 front & 285/35 rear or go for wider tires ?

Im not interested in looks .. i want to get the best of my car's handling performance

 

[2012-Boss]

You can mount up to a 275 width tire on the front 9" rim. For the rear, I would not go bigger than a 285 with the 9.5" rim width.

If the suspension is stock, you need to maintain a staggered tire fitment, either 255 front / 285 rear or 265 front / 285 rear on your existing rims. My preference is the 265 / 285 to dial out a little bit of understeer.

If you have an adjustable sway bar, then run the 275 / 285 which is the widest tires that will fit properly on your current rims.

If this is a dual purpose car and set of tires, I understand the PSS selection. If not, then I would look at your class rules and run the stickiest tire you can.

 

[eng90]

You can mount up to a 275 width tire on the front 9" rim. For the rear, I would not go bigger than a 285 with the 9.5" rim width.

If the suspension is stock, you need to maintain a staggered tire fitment, either 255 front / 285 rear or 265 front / 285 rear on your existing rims. My preference is the 265 / 285 to dial out a little bit of understeer.

If you have an adjustable sway bar, then run the 275 / 285 which is the widest tires that will fit properly on your current rims.

If this is a dual purpose car and set of tires, I understand the PSS selection. If not, then I would look at your class rules and run the stickiest tire you can.

I will be going for bmr sway bars later on so im not worried about getting a closer to square setup but my concern is if i go for the 275 in front ... would it outperform the 255 in handling and steering ? Or would the bigger size would bulge the tire and make handling or steering underperform the 255s ?

 

[eng90]

Another thing i would like to know is the height ratio for front and rear .. would it do change in handling and steering response if i go for same or go for taller tires ?

 

[2012-Boss]

Yes, the 275 on a 9" rim will provide more grip than the 255 and will not be pinched.

If you go wider in the front, either a 265/35/19 or a 275/35/19. Both are have a slightly shorter sidewall than the 255/40/19 which will result in a faster tire response.

My street tires are PSS 275/35/19 on a 9" front rim and 295/35/19 on a 10" rear rim. The 275 fits very well on a 9" rim. The 295 is definitely too wide for an 9.5" rim.

If the tires are for autocross, there are better performers even in "street" tires. The Bridgestone RE-71R is a lot better autocross / hpde tire than the PSS. It also has a 200 UTGQ tread wear rating which is mandated in some classes.

http://www.tirerack.com/tires/tests/testDisplay.jsp?ttid=219

http://www.minimumtread.com/bridgestone-potenza-re-71r-review.html

http://www.minimumtread.com/the-blend-line-hpde/track-tires-vs-performance-street-tires

 

[eng90]

Yes, the 275 on a 9" rim will provide more grip than the 255 and will not be pinched.

If you go wider in the front, either a 265/35/19 or a 275/35/19. Both are have a slightly shorter sidewall than the 255/40/19 which will result in a faster tire response.

My street tires are PSS 275/35/19 on a 9" front rim and 295/35/19 on a 10" rear rim. The 275 fits very well on a 9" rim. The 295 is definitely too wide for an 9.5" rim.

If the tires are for autocross, there are better performers even in "street" tires. The Bridgestone RE-71R is a lot better autocross / hpde tire than the PSS. It also has a 200 UTGQ tread wear rating which is mandated in some classes.

http://www.tirerack.com/tires/tests/testDisplay.jsp?ttid=219

http://www.minimumtread.com/bridgestone-potenza-re-71r-review.html

http://www.minimumtread.com/the-blend-line-hpde/track-tires-vs-performance-street-tires

The thing is where i live.. we have steep speed bumps and broken roads and im afraid if i go with the 275/35 the lt headers would scrape ... and for the rears ..

Do i go 275 to make a square setup or should i go for the 285 ? And do i need to get short sidewalls to or it will not effect the handling and steering if its for rear tires ?

 

[2012-Boss]

With a 275/35/19 the car will only be 1/4 inch lower in the front. You can't rotate the tires front to back with staggered rim widths, so there is no reason to run a square setup. Stick with the OEM 285/35/19 size in the rear.

Again you will need an adjustable sway bar to tune out any oversteer. My recommendation with factory springs is a stiffer front bar.

 

[eng90]

And would the difference between aspect ratio of 35 and 40 significent ? Or is that difference is negligable ?

My question is for front tires and rears.

 

[2012-Boss]

And would the difference between aspect ratio of 35 and 40 significent ? Or is that difference is negligable ?

My question is for front tires and rears.

I really do not understand the question. I am not sure what else I can add to the answers and recommendations I have already provided.

 

[Mad Hatter]

I ran 275/35-19 square on a stock suspension for about two years. Running the shocks at 5 up front and 3 in the rear was a great combo. The RE71R are a perfect choice as they can be switched from side to side, something that the PSS cant do. Running square saves you a ton of money as you juggle your tires.

My roads are pretty terrible, but with a header and the 275's on a stock suspension you should be fine.

 

[7500RPM_Ben]

Good thread, I have been searching for what people recommend to go with on stock Boss 302 wheels. It seems that staying with the stock size is the best. I am looking to switch tires in a year or so, I will most likely go with MPSS's or something like that.

 

[Mad Hatter]

Good thread, I have been searching for what people recommend to go with on stock Boss 302 wheels. It seems that staying with the stock size is the best. I am looking to switch tires in a year or so, I will most likely go with MPSS's or something like that.

Just too double highlight the point... you will lap faster with 275's upfront vs 255's

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[eng90]

I meant how big of handling difference i will expect if i go for 275/40 instead of 275/35 ? Hand how about rear from 285/35 to 285/40 ?

 

[Mad Hatter]

Not that much at all I think. But having a slightly smaller wheel does help you on small tight tracks. You have more tire selection with 275/35-19 as well.

 

[7500RPM_Ben]

Just too double highlight the point... you will lap faster with 275's upfront vs 255's

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Of course, due to the larger contact patch. My Boss will not see the track for a long time :.

 

[Flyboygsxr]

There are a lot of things to consider when selecting the proper tire for you vehicle and for your wheels. I'll see if I can offer some insight:

1. Advance Trac is programmed for a specific ratio between the front and rear tire sizes.
2. A Pirelli PZero 285/35/18 for example is not necessarily the same size as a Michelin PSS 285/35/18. The overall width, tread width, and overall diameter are different even though they are listed on the same size. Use Tirerack when comparing tires...they break down all the details on a tire including the tire weight.
3. Each manufacturer has a recommended rim width for each size of tire. There are some 305/35/18's I can fit on my 18x10" rims but some that I cannot because the manufacturer recommends a 10.5" rim.
4. Look at the treadwear rating for each tire you are considering and look at consumer reviews.

There are so many factors to consider...I hope I didn't confuse you anymore. Let me add you can never go wrong with the Michelin PSS. I think it's the best all around tire on the market today. It's got great grip, it's great in the wet, it's predictable, and it will outlast most other high performance summer tires.

Adam

 

[7500RPM_Ben]

There are a lot of things to consider when selecting the proper tire for you vehicle and for your wheels. I'll see if I can offer some insight:

1. Advance Trac is programmed for a specific ratio between the front and rear tire sizes.
2. A Pirelli PZero 285/35/18 for example is not necessarily the same size as a Michelin PSS 285/35/18. The overall width, tread width, and overall diameter are different even though they are listed on the same size. Use Tirerack when comparing tires...they break down all the details on a tire including the tire weight.
3. Each manufacturer has a recommended rim width for each size of tire. There are some 305/35/18's I can fit on my 18x10" rims but some that I cannot because the manufacturer recommends a 10.5" rim.
4. Look at the treadwear rating for each tire you are considering and look at consumer reviews.

There are so many factors to consider...I hope I didn't confuse you anymore. Let me add you can never go wrong with the Michelin PSS. I think it's the best all around tire on the market today. It's got great grip, it's great in the wet, it's predictable, and it will outlast most other high performance summer tires.

Adam

I have pretty much made up my mind on Michelin PSS's being next on my Boss, unless they end up being outrageously expensive in the future.

 

[Mad Hatter]

If its a street car that goes to the track...then the super sports are great..... if its a track car the drives on the street then I would go with 71R's

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