[Norskiepete]

I know that the offsets for my 93 968 are 65mm front and 55mm rear. I am shopping for some 17" wheels and understand that many of the non-968 wheels (ex: 996, Boxter) will fit if spacers are used to accomodate different off-sets. Can someone recommend a good source for the spacers? I am looking at a set of 2-pc 993 Targa wheels that list the off-set at 55 for both front and rear. Will these fit? Are there other guidelines to follow or problems to avoid?



PEte

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[Greimann]

55 offset all around should work fine. Do you have the full specs on the wheels and the tires you plan to mount?



If you did need spacers, Performance products has 1/4" spacers for a good price:

http://www.automotion.com/productpage.aspx...acers+and+Studs

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[Norskiepete]

sorry to sound ignorant here, but most of the ads I see only list the model it came from, size (17", 18", etc) and the offsets. What other specs should I be looking for?



Pete

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[Greimann]

A wheel has 3 dimensions. Diameter, offset and width. You have diameter and offset so we need the width. More than likely they will be 7 to 8 inches up front and 9 or 10 in the back, but an informed seller will have this info readily available.



Also, what tires do you plan to mount? This dimension is going to be something like 255/45-17 or 265/35-18. When determining fitment, you need to know where the rubber is. 17" wheels usually carry rubber that easily fits the 968, but venturing into the 18" sizes you need to pay attention to widths and offsets very carefully.

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[BruceWard]

Dave has a very helpful wheel fittment caclulator in the technical section of his website http://968engineering.com/images/wheelcalculator.xls . If you input the diameter, width, profile and offsets into the calculator it will work out the changes for you.



993 Targas have very nice wheels. If you do not buy them I would love a chance to do so.







A 993 Targa for her is probably the most likely Porsche to end up sharing our garage.

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[flash]

to elaborate a bit on what dave said, things to consider too, especially if you choose 18s, are tire sizes - keep in mind the outside diameter and actual width of the tire when figuring out what you want - they vary brand to brand, as much as an inch in width within the same size - this can present a big problem if the wheel you choose is close to one of the limits, and you choose a wide brand - most of the brands have their information up on the tire rack site, so you can look at the specs and then make a choice

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[BruceWard]

Pete,



993 Targa wheels are very nice, German looking, 17 x 7 & 9 inch wheels. They are very well suited to our cars and should not need spacers or have with issues with reasonable sized tire installed. I suggest using the factory 17" tire sizes of 225/45/17 and 255/40/17.



If the 993 Targa wheels come with tires on them they are likely to be a 205/255 combination which is suited for the balance of a 911. With the balance of the 968 it will handle better with the wider tire up front. But several 968 owners have driven on 205/255 setups after buying 911 wheels.



Flash,



Are you referring the the width of wheel needed when you say "vary brand to brand, as much as an inch in width within the same size" or are you saying that the outside width of a tire rated at 275mm (11 inches) may actually be anywhere from 250mm (10 inches) to 300mm (12 inches) in width? I can see plus variations on SUVs and other vehicles where the tires bulge out when fully inflated. But our low profile tires have very little bulge. I can not image a vendor selling a tire that is an inch narrower than they market it as.

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[flash]

yes, i am referring to the tires - take a look brand to brand - it will shock you - for example, in the 255/40 S0-3 that i had, versus the michelin pilot sport that ron has, there was about 3/4" difference in width - same size tire



in further searching, i found some very large differences - you really have to take a close look - you can't say that 255 is 10" and call it a day - it just isn't so



beyond that, the shoulder profile plays in too - so does the sidewall composition - a soft sidewall tire, like the michelin, will flex more under load, potentially causing more problems if near a limit, than will a firm sidewall tire, like an S0-3 - however, the soft sidewall tire wil ride smoother and quieter



all tires are not created equal

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[Greimann]

[quote name='flash' date='Dec 4 2005, 05:09 PM']all tires are not created equal

[right][post="13086"]<{POST_SNAPBACK}>[/post][/right][/quote]

Just to add, My 265 Continental Sport Contact 2's were significantly wider in section than my 275 Yoko ES 100's. I don't have my notes, but is is easily 1/4 to 1/2" difference. Strange but true, believe it or not!

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[Anchorman]

Definitely something I'll have to consider at tire replacement time. Anything wider than my current 275-18 35 on the rear (Yokohama AVS-100) would result in unacceptable fender interference.

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[Tom in Austin]

I've had 911 wheels with OEM 205/55 tires on my 968 for about a year and a half now. The narrower front wheels and tires (vs. 968 spec) did seem to slightly alter the dynamics.



So my question is, when new tire time comes, if I go to a wider front tire (maybe a 215 or 225 width) on these 7"-wide wheels, will that cause a loss of sidewall stiffness that undoes the value of the wider contact patch?

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[Norskiepete]

Thanks for the information. Based upon some of the comments I have read here and on 968.net regarding ride quality, I am going to steer away from 18's and stick to 17's. The targa wheels are 7"/9" wide, without tires. The price is reasonable; it's just a budget timing issue right now.



Pete

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[flash]

tom - the general answer is yes - the more specific answer is dependent on the particlular tire - if you are going to oversize on a rim, make sure you go with a stiff sidewall tire, or you could easily get tire roll in a corner - it will feel soft and compliant right up to the point where it releases - what you get then is a bit of snap back and wiggle



the sizes you are talking about are still within the recommended limits for the tire, and the problems or complications won't be huge, but they will be there - i have done the same thing on my jeep for the same reasons - i wanted more contact for towing stability, and a large tire for ride comfort - the tradeoff is a bit of twitch and wiggle when the tire releases side load



rule of thumb - one size up is no biggie - 2 is pushing it - 3 is noticable issues



one way of compensating is to lower the profile (going from a 45 to a 40) - check your OD and see if you can find a tire in the width you want with a lower profile and still make your OD limits

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[BruceWard]

Tom, if you look through the tire size charts on Tirerack.com they will list the range of wheel widths that work with the tire and the optimum wheel width. You should be able to find a 225/45/17 that has an optimal fit on a 7" wheel, but most will work fine on a 7" wheel.

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[flash]

if you look at the specs, you will see that they all spec 7"-8.5" for rim width



7 is the absolute narrowest rim you can run a 225/45/17 safely



the optimum is 7.5-8



a wider rim means stretching the tire and having more breakaway issues - a narrower rim means more sidewall flex and twitch and release issues



again though, this is more dependent on the sidewall construction and properties of the specific tire - a 225/45/17 SO-3 will not feel anything or react anything like a 225/45/17 michelin pilot sport - both great tires - very different construction and characteristics



so, the real question is "what kind of ride are you looking for?"



then, you can decide soft or firm, wide or not, 45 or 40, yada yada

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[sparky]

Pete

I use 2003 Boxster S wheels on my 968CS. Sizes are 17x 7 and 17x8.5 offsets are 55mm front 48 rear. They fit perfectly without spacers but in my case ...



I have also added 17mm spacers to front to further increase the track. So I am running 55 -17 = 38mm front offset (compared to stock 65mm). So my wheels are 2 x 37mm further apart and they fit *perfectly* and don't rub with 225/45/17 tyres. (This improves turn-in when running hard on track)



Rears are fittted as-is with no spacers and 255/40/17 tyres. (See pix under flash's thread about "needing to be more grounded")

grounded thread

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