16"s vs. 17"s

[Old_skool_bmw]

Hi Guys,
If you're running a standard diff and 280hp at the fly is there going to be a major difference in car performance in running 16"s or 17" rims.. with 225/45/16 all round or 215/40 & 245/35/17??

Thanks,
Laurence.

[WBSAK03]

As long as the OD and wheel package weight are equal, no. On the other hand, there will be a performance gain at some tracks where the particular overall gearing is more ideal. This is, however, on a track-by-track basis.

Christopher

[Old_skool_bmw]

I would look to use either 16 BBS RS or 17 BBS RS. As far as i know the 16's have the advantage in that you can run tarmac tyres but they don't make them in the right size for 17's, but on the other hand running 17's wold allow a bigger BBK and extra clearance on 320mm rotors etc.

Obviously gearing plays an important role... but what you're saying is that if the weight an overall size is the same they should be as good as eachother??

Can yuou see any problems running wider 254/35's on the rear for 9"s and 215/40's on the fronts??

Laurence.

[WBSAK03]

I would look to use either 16 BBS RS or 17 BBS RS. As far as i know the 16's have the advantage in that you can run tarmac tyres but they don't make them in the right size for 17's, but on the other hand running 17's wold allow a bigger BBK and extra clearance on 320mm rotors etc.

Obviously gearing plays an important role... but what you're saying is that if the weight an overall size is the same they should be as good as eachother??

Can yuou see any problems running wider 254/35's on the rear for 9"s and 215/40's on the fronts??

Laurence.

Performance difference would be negligible, given the same weight/OD. The 17s would provide a smaller aspect ratio over 16s, giving you less sidewall to flex under cornering. 254s will not work out back, and are too wide for a 9 inch wheel, IMO. Additionally, a staggered set-up will produce a lot of understeer - especially with the width differences you mentioned. You could do a 245 (9 inch wheel) out back with a 235 (8 inch wheel) up front. This will give you an aggressive staggered look, without a whole lot of additional understeer. Perhaps a 235 rear (8 inch wheel), 225 (7.5 inch wheel) front set-up would be best, and easier to accomplish. I run 235/40/17s all around on an 8 inch wheel (ET20) and love it. The key is additional front negative camber (and the removal of the front fender liners). -2 to -2.5 degrees up front works well for me.

Christopher

[paintpro21]

I run 235 all around on a 17". -2.8 camber upfront and I still have my fender liners. When I put new liners in, had I have taken a heat gun and shaped them properly (from the factory they were deformed) they would been in better shaped. but no problem the tires "self clearanced" themselves hehe

[Dougy Fresh]

i was debating this some time ago, i ended up getting bbs rs 16x8 rear 16x7 front et11, i am running 215 45 falken azenis all around handling is very nice and they are pretty close to the stock wheels as far as weight is concerned. i do not have a problem with understeer.

i believe there is only a negligible difference between 16s & 17s with 280hp i don't think you will be able to notice.

if you are planning on upgrading to a bbk i would get the 17s for brake clearance.

[Old_skool_bmw]

im thinking getting 17x8.5 all way round and running 245/35's all 4 corners.
Would 245/35 be too big up front?

Laurence.

[Dougy Fresh]

Calculating tire size from tire rack:

Section Width

Following the letter(s) that identify the type of vehicle and/or type of service for which the tire was designed, the three-digit numeric portion identifies the tire's "Section Width" (cross section) in millimeters.

P225/50R16 91S

The 225 indicates this tire is 225 millimeters across from the widest point of its outer sidewall to the widest point of its inner sidewall when mounted and measured on a specified width wheel. This measurement is also referred to as the tire's section width. Because many people think of measurements in inches, the 225mm can be converted to inches by dividing the section width in millimeters by 25.4 (the number of millimeters per inch).

225mm / 25.4 = 8.86"

Sidewall Aspect Ratio

Typically following the three digits identifying the tire's Section Width in millimeters is a two-digit number that identifies the tire's profile or aspect ratio.

P225/50R16 91S

The 50 indicates that this tire size's sidewall height (from rim to tread) is 50% of its section width. The measurement is the tire's section height, and also referred to as the tire's series, profile or aspect ratio. The higher the number, the taller the sidewall; the lower the number, the lower the sidewall. We know that this tire size's section width is 225mm and that its section height is 50% of 225mm. By converting the 225mm to inches (225 / 25.4 = 8.86") and multiplying it by 50% (.50) we confirm that this tire size results in a tire section height of 4.43". If this tire were a P225/70R16 size, our calculation would confirm that the size would result in a section height of 6.20", approximately a 1.8-inch taller sidewall.

[WBSAK03]

im thinking getting 17x8.5 all way round and running 245/35's all 4 corners.
Would 245/35 be too big up front?

Laurence.

245s on an 8.5 inch wheel will be pinched. Also, 245s up front will be difficult without a lot of negative camber and precise spacing. I would stick with 235s all around on the same 8.5 inch wheel.

Christopher

[Old_skool_bmw]

Just called the tyre shop.
They recon you can run a 245/35/17 tyre on anything from 8 - 9.5" wide. So 8.5" would seem to be a good fit for the tyre size.

I know that the 245/35/17 has the same rolling radius as the 205/55/15's OEM on my e30 M3. Hmmm,might look into it a bit more.

Laurence.

[M3 Adjuster]

Just called the tyre shop.
They recon you can run a 245/35/17 tyre on anything from 8 - 9.5" wide. So 8.5" would seem to be a good fit for the tyre size.

I know that the 245/35/17 has the same rolling radius as the 205/55/15's OEM on my e30 M3. Hmmm,might look into it a bit more.

Laurence.

Toyo makes the T1-R . I believe goodyear makes an Eagle F1 in this size also. Indeed, you will need to be careful with spacers and wheel combo.. I would recommend you have a shop fit one and test on the front. This combo has definitely been done in the past with the Toyo.

[M3 Adjuster]

Calculating tire size from tire rack:

Section Width

Following the letter(s) that identify the type of vehicle and/or type of service for which the tire was designed, the three-digit numeric portion identifies the tire's "Section Width" (cross section) in millimeters.

P225/50R16 91S

The 225 indicates this tire is 225 millimeters across from the widest point of its outer sidewall to the widest point of its inner sidewall when mounted and measured on a specified width wheel. This measurement is also referred to as the tire's section width. Because many people think of measurements in inches, the 225mm can be converted to inches by dividing the section width in millimeters by 25.4 (the number of millimeters per inch).

225mm / 25.4 = 8.86"

Sidewall Aspect Ratio

Typically following the three digits identifying the tire's Section Width in millimeters is a two-digit number that identifies the tire's profile or aspect ratio.

P225/50R16 91S

The 50 indicates that this tire size's sidewall height (from rim to tread) is 50% of its section width. The measurement is the tire's section height, and also referred to as the tire's series, profile or aspect ratio. The higher the number, the taller the sidewall; the lower the number, the lower the sidewall. We know that this tire size's section width is 225mm and that its section height is 50% of 225mm. By converting the 225mm to inches (225 / 25.4 = 8.86") and multiplying it by 50% (.50) we confirm that this tire size results in a tire section height of 4.43". If this tire were a P225/70R16 size, our calculation would confirm that the size would result in a section height of 6.20", approximately a 1.8-inch taller sidewall.

Ok... well the info is correct... it's the tire manufactures that lie..

Keep in mind that each manufacturer actually prints the widths of their
tires in their data and tech shees on their web sites.. A Hoosier 225/40/17 is *way* fatter than most
235/40/17s . Don't expect to be able to compare Birdgestones to Yokos to Kuhmos any more than you can
be confident that a size 10 Nike is the same as a Reebok or Addidas .

go to the manufacturers web sites and look up their tire data! :yowzah:

[Dougy Fresh]

that conversion method has worked accurately for me with dunlop and falken.

when you say the tire companies lie, what is the variance between these tires?

[WBSAK03]

Here's a tip:

When I was fitting 245/40/17 Hoosier R6s and Team Dynamics Pro Race 1.2 17X9s - E36 offset - on a customer's E30 M3 race car, I ordered only one tire and one wheel at first. I wanted to be sure we could make them fit before spending a lot of money on the complete set. I used the one wheel to test fit, fabricate spacers and complete general modifications before knowing for sure we could make them work on all four corners. Then we went ahead and made the complete set investment.

If it didn't work, we would only be out a few buck, rather than the whole nut.

Christopher

[martin]

i run 17 x 8 with 245 35 17 all round et20 with a 7mm spacer allround so et13
no liners though and that is fine 2.5 deg neg camber allround