[rick j.]

Hi all,



I've had my '93 968 coupe tip for about three wonderful years now. Up til now, I mostly frequent the 968.net board, but I did sign on here as a member about a year ago. Unfortunately, I haven't had a chance to contribute all that much here. Last year was a bit of a blur, as we completed an intense three year project at work to replace all my firm's financial business systems with SAP systems.



In addition, my father passed away last summer at age 81. I am thankful I spent the last 15 years visiting my parents in Florida 2-3 times a year, as well as accompanying them on several vacations in the last few years.



FYI, If your folks are still around, find the time to visit with them as much as you can *while* you can.



A few weeks ago, I posted on 968.net that I went over a pothole one night in early January on the way home from the movies. The next morning my tire was flat. I put 2 new tires on in the rear (Michelin Pilot Sports) and the tire wouldn't hold air for more than a day or two. Took it in and my shop found a small crack in or near the flange of the right rear wheel (where I incurred the original flat). They sealed the crack, but recommended getting a new wheel.



After unsuccessfully bidding on some exact replacement wheel (993 Cup II wheels), I decided to take a different path, and buy a set of 18" Speedline Corse wheels. The wheels were listed here in the For Sale forum. I got a nice price on them because they are slightly odd size (8x18 fronts, 9x18 rears). The wheels are sitting in my living for now, until I save up for a new set of 18" tires.



Can someone confirm for me the best or optimim 'size' of tires for these widths ?



I'm told by a friend to use 225/40/18 tires for the 8x18 front wheels, and 265/35/18 for the 9x18 rear wheels, but the 265/35 spec seems a bit large for 9" wide wheels? I've noticed that 265/35 size can also fit on 10x18, so I just want to make sure they're not too wide for 9x18 wheels.



Your thoughts?



Thanks in advance.



- rick

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[rustech]

As you might know, the stock 7.5s come with 225s while the stock 9s come with 255s.



On you new wheels, I would put 235's on the front 8s and cheat the backs by putting slightly larger 265s on the 9s to keep the same differential front to rear.



Good luck.

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[BruceWard]

My 968s has 235 front and 265 rear on 18s for street tires.

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[flash]

check the O.D. - i'd look for tires that make 25" (the stock O.D.)



that would be a 255/35/18 rear and a 225/40/18 front



they will still be wider than what was on the 17s, even though the size is the same - 225 is not 225mm in all profiles - they will also be stiffer



tire rack has a pretty good info chart with the real dimensions for each brand tire - take a look

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[Richard]

Can he also run with a 20mm difference in tire size since his wheels are only a 1" difference in width unlike the 1.5" difference on the Cup wheels? I ask because the stock 16” wheels use tires that are 20mm in difference. For example, on my stock 16" wheels with 7" fronts and 8" rears, I am running 225/50 on the front and 245/45 on the rears. These were the maximum size that Tire Rack recommended.

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[flash]

well, the short answer is yes



this has been discussed at length - sidewall stiffness plays a large part in determining what happens to the handling, cornering (they are different) and ride comfort when you oversize, and that varies a lot from tire model to tire model - generally speaking though, a properly fitted and stretched tire will outhandle a larger tire of the same model on the same size rim, though the larger tire may outcorner it - the larger tire will also provide more ride comfort, at the expense of a bit of acceleration



if you go 20mm bigger in width, you gain height if you don't adjust aspect ratio - that will throw off the speedo and gearing a bit, losing a little out of the hole, but probably helping a bit up top and in fuel economy (depending on the weight of the wheels and tires)



he could also run into clearance issues, depending on other factors like offset, ride height, camber angles, etc



lots of stuff to look at to make a choice that fits what you want - within reason, no really wrong answers though - just choices

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[Greimann]

[quote name='rick j.' date='Feb 22 2006, 02:52 PM']....

Can someone confirm for me the best or optimim 'size' of tires for these widths ?



I'm told by a friend to use 225/40/18 tires for the 8x18 front wheels, and 265/35/18 for the 9x18 rear wheels, but the 265/35 spec seems a bit large for 9" wide wheels?  I've noticed that 265/35 size can also fit on 10x18, so I just want to make sure they're not too wide for 9x18 wheels.

[right][post="16402"]<{POST_SNAPBACK}>[/post][/right][/quote]

The most direct answer to your question is found at the SPECS table at Tirerack's site. For example, here is the table for the Yoko AVS ES 100's

http://www.tirerack.com/tires/Spec.jsp?mak...model=AVS+ES100



There are other tables for your brand of chioce, but the 265's would be a good fit for the rears and they are rated for the 9" wheel rim width.

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