Planet-9 Porsche Forum banner
1 - 19 of 19 Posts

·
Registered
Joined
·
1,378 Posts
Discussion Starter · #1 ·
I am considering upgrading wheels and tires on my 2007 boxster S and have read a number of posts on here about aftermarket vs. replica vs. OEM. The conclusion seems to be that replica and likewise inexpensive aftermarket wheels are about 5lbs heavier on each corner than OEM BBS wheels which some people believe makes a difference in street application and others disagree.

My recent issue of Car and Driver arrived at my door yesterday and they had an artical testing exactly this theory. They had a VW with stock 15" rims, then tested the performance difference with 16, 17, 18, and 19" wheels and tires on the same car. All of the wheels were the same ASA wheels from tirerack, and as they size went up, so did the weight. I was amazed to see how adding a few lbs from one size to the next changed the perfomace so drastically. Adding 3 lbs going from the 17" package to the 18" was a half second slower to 100mph and lost a full mpg on fuel economy... the tradeoff was an additional .04g on the skidpad.

The difference from stock to the 19" wheel package and the stock 15" is 14lbs on each corner and the numbers are staggering. .4 seconds slower to 60, aa full 1 second to 100mph, and fuel economy went down 2.2mpg on thier test loop.

This really made me realize that even if you do not track you car, weight can and does make a difference in everyday driving, especially fuel economy. I am deffinatly going to stick with OEM upgrades and make sure I shop for tires according to weight as well... The new Continental DWS and DW tires on tirerack seem to have excellent reviews so far, have great treadwear ratings and to top it off, they seem to be a few lbs lighter on each corner than some of the more expensive OEM tires as well.
 

·
Registered
Joined
·
621 Posts
Hi Daniel,
Good points all. I haven't read the article yet, but have a pretty good background. A few things to keep in mind:
- OEM isn't necessarily the best choice. With Porsche OEM, you are guaranteed a good quality reasonably-lightweight wheel. But, unless used, they are expensive.
- Aftermarket wheels of course come in a broad ranges of qualities, weights, and styles - for a given size even. Some are much lighter than OEM. Some are much heavier.
- By careful selection of wheels and tires, as you mention, one can optimize. For example, my OZs are similar to or lighter than OEM, but larger in wheel diameter and much wider - for less money than OEM. For higher budgets, some of the one-piece forged wheels are better-still.
- The acceleration numbers you mention do not surprise me - as most of the weight gained is near the OD of the wheel/tire assembly - the equations are a bit involved, but this has a very large effect on rotational inertia. Unsprung weight/inertia are also affected, and even gyroscopic effects are seen. Good luck.
 

·
Registered
Joined
·
239 Posts
On the Golf, traction may not have been much of an issue with the 15" setup, so potential additional forward traction gained from the larger setups may not improve acceleration times. I think with the Caybox S twins, more traction could be used at launch and driving out of corners, so the difference in acceleration times might be much smaller.

Also, I suspect that the Golf 15" tires were likely chosen for good fuel economy numbers, too. (You'll note that the 18" tires in the test were 'W' rated, while the 17"s were 'V' rated, IIRC. This means that some parameters of the tire design were different, and likely optimized for different things - traction and turn-in being more emphasized in the 'W' tires, plus perhaps a stiffer and/or stronger structure to sustain higher speeds.) With a 987S, the stock tire packages are likely already chosen as to emphasize traction, turn-in, stability and handling feel, rather than fuel economy or even acceleration times.

I'll bet that the differences in weights will have much less effect on our cars than were shown in the C/D test.

Personally, I think Jeff G in NE GA has found one of the best combos of weight, looks, fit, quality and cost around.
 

·
Registered
Joined
·
1,395 Posts
ASA wheels are not really the best example of the aftermarket's potential for quality, lightweight and rigidity :)

There are far better options than OEM in the aftermarket! One must make sure to properly research his options and it will ultimately come down to your budget. If you're used to shopping for OEM replacements, you should have no problem stepping into the "forged wheels" aftermarket and get a definitive improvement over your OEM wheels.
 

·
Premium Member
Joined
·
383 Posts
I am considering upgrading wheels and tires on my 2007 boxster S and have read a number of posts on here about aftermarket vs. replica vs. OEM. The conclusion seems to be that replica and likewise inexpensive aftermarket wheels are about 5lbs heavier on each corner than OEM BBS wheels which some people believe makes a difference in street application and others disagree.

My recent issue of Car and Driver arrived at my door yesterday and they had an artical testing exactly this theory. They had a VW with stock 15" rims, then tested the performance difference with 16, 17, 18, and 19" wheels and tires on the same car. All of the wheels were the same ASA wheels from tirerack, and as they size went up, so did the weight. I was amazed to see how adding a few lbs from one size to the next changed the perfomace so drastically. Adding 3 lbs going from the 17" package to the 18" was a half second slower to 100mph and lost a full mpg on fuel economy... the tradeoff was an additional .04g on the skidpad.

The difference from stock to the 19" wheel package and the stock 15" is 14lbs on each corner and the numbers are staggering. .4 seconds slower to 60, aa full 1 second to 100mph, and fuel economy went down 2.2mpg on thier test loop.

This really made me realize that even if you do not track you car, weight can and does make a difference in everyday driving, especially fuel economy. I am deffinatly going to stick with OEM upgrades and make sure I shop for tires according to weight as well... The new Continental DWS and DW tires on tirerack seem to have excellent reviews so far, have great treadwear ratings and to top it off, they seem to be a few lbs lighter on each corner than some of the more expensive OEM tires as well.
Daniel,
You are on the right track, unsprung wieght is very important and is something that most people don't think about unless they are doing serious tracking or racing. I have not read the CD artical however it sounds like an apple to apple comparison. Most people are chosing wheels on looks and figure that 19" are the best size since they cost most. The best selection and value for tires and wheels are 17" & 18", you should compare used OEM to quality aftermarket wheels. Good luck.
 

·
Registered
Joined
·
1,378 Posts
Discussion Starter · #7 ·
Thanks for all the advice guys, I think I am going to stick with OEM but get refinished versions to save a ton of cash... Looking at the sport design 19", I know that the 18" boxster S wheels I already have are the preferred wheel but I can't help but like the way the 19" look much better. I can pick up the sport designs re-finished for about $1400 for the set, so the only thing in that budget are a few quality aftermarkets, like the OZs, or victor equipment, or else replica wheels where who knows what you get... I think I am going to stick with the re-finished sport design 19s...
 

·
Registered
Joined
·
9 Posts
Forgestar's F14 in 19s are right at 1,400 + S/H. Lighter than OEM and are custom made to your desired specifications (width, offset, finish)

Think about it :)




Those actually look a lot better than I would have imagined on a Cayman...

What color are those, do they come in 18s that are a bit wider than stock & are those $1199?

TIA...
 

·
Registered
Joined
·
1,395 Posts
Those actually look a lot better than I would have imagined on a Cayman...

What color are those, do they come in 18s that are a bit wider than stock & are those $1199?

TIA...
Those are 19s in Gunmetal. We recommend 18x8.5 front and 18x10 rear. You can go up to an 11" at the rear. The 18s are indeed 1199 + S/H for the set.
 

·
Registered
Joined
·
9 Posts
Those are 19s in Gunmetal. We recommend 18x8.5 front and 18x10 rear. You can go up to an 11" at the rear. The 18s are indeed 1199 + S/H for the set.
How is the durability? I'd be using them @ the track w/ R-comps (deflection etc) & possibly on the street (potholes etc).

Also, do you offer tire/wheel pkgs?

How much are the forged version in those sizes & how much do they weigh?

Thx
 

·
Registered
Joined
·
9 Posts
How is the durability? I'd be using them @ the track w/ R-comps (deflection etc) & possibly on the street (potholes etc).

Also, do you offer tire/wheel pkgs?

How much are the forged version in those sizes & how much do they weigh?

Thx
Called Forgestar directly abt above questions--looks like the regular F14s will get the job done & the forged wheels are ~3-4# heavier.

Still have the question abt wheel/tire packages...

Thx
 

·
Registered
Joined
·
139 Posts
This thread is of interest to me because my '08 base Cayman came with the optional 18" wheels and rims, and I've been considering the idea of swapping my rims with someone who wants to upgrade from 17" rims to 18" rims so I can use 17" tires. One thing that gives me pause is that the tires which Porsche specifies for their 17" rims come in an unusual size which is not available from very many tire makers. I'm wondering:
1. How people who are using the 17" tire/rim combo like it?
2. What tires they are using, and how they like them?
3. Would they recommend a tire other than the one they're using?
4. Has anyone tried out tires in sizes other than that specified by Porsche on their 17" rims, and how did that go for them?

Thanks,

ThomWT
 

·
Middle-Aged Porsche Punk
Joined
·
999 Posts
Thanks for all the advice guys, I think I am going to stick with OEM but get refinished versions to save a ton of cash... Looking at the sport design 19", I know that the 18" boxster S wheels I already have are the preferred wheel but I can't help but like the way the 19" look much better. I can pick up the sport designs re-finished for about $1400 for the set, so the only thing in that budget are a few quality aftermarkets, like the OZs, or victor equipment, or else replica wheels where who knows what you get... I think I am going to stick with the re-finished sport design 19s...
It's just that Porsche gives you 2 options with the 18" wheels on the 987 and a cornucopia of 19" options (including most variants of the 997 wheels, sized narrower for the Boxster and Cayman).
 

·
Middle-Aged Porsche Punk
Joined
·
999 Posts
This thread is of interest to me because my '08 base Cayman came with the optional 18" wheels and rims, and I've been considering the idea of swapping my rims with someone who wants to upgrade from 17" rims to 18" rims so I can use 17" tires. One thing that gives me pause is that the tires which Porsche specifies for their 17" rims come in an unusual size which is not available from very many tire makers. I'm wondering:
1. How people who are using the 17" tire/rim combo like it?
2. What tires they are using, and how they like them?
3. Would they recommend a tire other than the one they're using?
4. Has anyone tried out tires in sizes other than that specified by Porsche on their 17" rims, and how did that go for them?

Thanks,

ThomWT
Nice color on your car by the way. :)

I have the standard 17's. The 205-55 and 235-50 sizes (front and rear) are actually relatively easy to find and definitely cheaper than for 18's and WAY cheaper than for 19's. They are Z-rated, N-designation performance tires (in my case PS2's) just like for the 18" and 19" wheels.

You will read plenty on other threads. General consensus is 17's ride better and will wear better thanks to the fatter sidewalls, but the 18's and 19's look better. I like the look of the 17's from a retro perspective, but next to other Caymans I've realized it looks quite odd, especially when people ask "wow, are those overinflated?"

I'd be tempted to trade but I only have one set of wheels. I am looking for 18's for summer use (my tires are in good shape now but will likely need replacement in about 5000 miles) and using my 17's with snow tires.
 

·
Registered
Joined
·
139 Posts
Engr1,
Thanks for your reply. It's clear as to how much you like the color.
When I saw this particular car on the lot I couldn't take my eyes off it, though I had arrived at the dealer's with the full expectation of getting the blue. I like the Brit Racing green a lot too, but somehow Ruby Red seems perfect. And up to now I was never interested in red for any of my other cars. I had a Kalahari Beige 530 that was stunning.
I have looked primarily on the Tire Rack website for the 17" tires and only found maybe half a dozen sets. My problem is that tread life on the PS2s is not great, and the Continentals I've had in the past were quite noisy.
My Cayman is my daily driver, and I'm almost always a fairly conservative to normal driver (though what constitutes normal in the Commonwealth of MA is debatable)--so I'm looking for comfort and durability as well as performance. I drive snows in the winter on 17's that I got for that purpose. My ideal tire would be a high performance all-season (that will handle messy weather and colder temps on either side of the winter season) that is comfortable and not noisy, and that won't require replacement every year or so--since I drive more than the average number of miles each year.
I don't mind the retro look so much--it reminds me of the MG I had too many years ago, and I'm mindful of the many benefits that come with a somewhat narrower and lighter tire.
If you can make a recommendation I'd be open to hearing what you think.

ThomWT
 
1 - 19 of 19 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top