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i have a wide body 356 Porsche replica and I’ve been trying to find out what size wheels and tires is best used. It currently has custom vintage wheels 245/50/15 on rear and 225/50/15 on front. The wheels were custom built 4.5 inch to wider version back in 1997. It looks like the tires from 1997 was over kill for this car. I’d like to change to a Fuchs, something similar or keep the same vintage wheels (cost savings) but need street legal FOT approved tires.  Any thoughts please let me know. Any ideas on what the vehicle was?20B43E14-AFAE-4A42-AEA8-7156373160D472108BF9-460A-4288-A9E1-931DA0ACC0D0 (356 wife body kit=15, 16, 17 inch wheels and size tires)

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6 or 7" wide wheels with 195's or 205's on the front (anything bigger is too much mass for the suspension) while 7's or 8's with 225's on the back should work really well. Too bad you think the 245's on the back are too big- I'm of the opinion that if they fit, the wider the better! I say this because Porsche has gone to wider and still wider wheel/tire combos on the back of their rear engine'd cars over the years in an effort to tame handling- I saw 315's on the back of a new I forget what a couple of years ago.  I think it's to make the cars more appealing to a wider customer base.

Maybe think about going to 16" diameter as there's just no tire selection in 15" any more (225/50-15, for example, is non-existent, and so many other 15" sizes are only available in all weather) and 16" polished Fuchs do look great on wide body'd Speedsters! Al

I have a CMC widebody with original Fuchs from a Porsche 911.  The suspension is IRS, not swing-arm with 3/4" anti-sway bars front and rear.

I have had 16" wheels on it since day one.  Earlier, I ran 6" wide rims on the front with 205X50 tires, and 7" wide on the rear with 225X50 tires.  That's a lotta tire on te ground!  The 205X50's on the front duplicates the outer tire diameter of the earlier VWs and leaves you with a speedo that's off by about 5% - 8% on the VDO replica speedos.  That wheel/tire combination was dynamite for handling - Best handling package I have ever had.  You will have to run wheel spacer/adapters to get the wheels out into the wheel well - I have 1-1/8" thick ones all around, made of Billet Aluminum and bought from Pelican Parts.  They're about $125 each and worth it.  they custom make them to whatever thickness you need.

Originally, I had Continental tires (don't remember the model) which had stiffer sidewalls.  After 12 years of running that combo, I traded my rear wheels for a pair of 6" Fuchs and now run 205's all around (Michelin).  I am also older and no longer corner as hard as I used to, so I have yet to feel the rear start to let go and never got it to let go even when pushed really hard with the 225's back there.

Hope this helps.  gn   They look cool, too!

IMG_2741

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Last edited by Gordon Nichols

Those are OEM Kronprinz (KpZ) "crown prince" wheels. Made in the German town of Solingen. Date produced is in circle and looks like 10/66 so they were on a '67 912/911. The 3.7 is thickness of metal in mm -- 3.9 mm is also seen on other year wheels.

If you think they are too far inset - you can add spacer to bring them out BUT be sure you increase the length of the studs to compensate.  I think steel wheels have a racer look but Fuchs are always a great alternative.  Your old steel wheels have some value to an Early Porsche racer so don't just recycle them.  Fuchs (German for Fox) come in may different sizes and offsets.  Early ones with a heart stamped on inside are ridiculously expensive. I'd personally go with replicas - just ensure offset is correct.  There is a chart of OEM offset posted here in another thread (might have come from Pelican).

Here's a link to an OEM KpZ wheel on eBay for $250 (for one not so pretty wheel)-

https://www.ebay.com/itm/Porsc...hVxaFDOd&vxp=mtr

The nice thing about real Fuchs wheels is that being forged, they are strong (they don't break like cast aluminum), repairable (not so much with a cast wheel if something does happen) and they are light; a steel 15x6" wheel weighs in the neighborhood of 20 or 22 lbs. where the same size Fuchs weighs just over 12 lbs. The 16" Fuchs wheels weigh just 1- 1 1/4 lb. more than the same width 15" wheel. Even a cast Fuchs copy weighs 4 lbs more than an original (the same size).

ALB posted:

6 or 7" wide wheels with 195's or 205's on the front (anything bigger is too much mass for the suspension) while 7's or 8's with 225's on the back should work really well. Too bad you think the 245's on the back are too big- I'm of the opinion that if they fit, the wider the better! I say this because Porsche has gone to wider and still wider wheel/tire combos on the back of their rear engine'd cars over the years in an effort to tame handling- I saw 315's on the back of a new I forget what a couple of years ago.  I think it's to make the cars more appealing to a wider customer base.

Maybe think about going to 16" diameter as there's just no tire selection in 15" any more (225/50-15, for example, is non-existent, and so many other 15" sizes are only available in all weather) and 16" polished Fuchs do look great on wide body'd Speedsters! Al

I like the width of the back but I’m having trouble finding tires for them as I was just able to find 245/60/15. Do you think the 60 would be too high vs the 50. Do you think the front is too wide. It rides good on a flat surface but when uneven it wants to dart to the sides. Thanks for all of your input. I’d like to keep using the wheels and just purchase tires but having problem finding rear size tire. Thanks again and I’ve been missing out on this site as you guys know a lot. Thanks

You generally want to keep to a 24-25" tall tire, as anything too tall ( and a 245/60-15 at 26.6" is too tall!) affects the overall gear ratio and slows down acceleration too much. As I said earlier, 15" diameter sizes are fast disappearing so I don't know what else to tell you (other than I wish 225/50-15's were still around!). And yeah, as I said before, I think 225's are too much for the front.  Al

The "darting to the side" may be caused by "bump steer" or a front end that needs alignment.  Have someone do a 4-wheel alignment as if it were a 1967 (swing-arm) or 1970 (IRS rear).

Have them set the front caster to around 5º to 7º.  For that you'll need a couple of sets of caster shims:

http://www.cbperformance.com/s...ter+shim&Submit=

Get two sets of shims and one set of bolts and give them to the person doing the alignment.

 

Stock size tire was 165/80x15 - I'd go with 225/60x15" which is very close to OEM tire size so speedo will be close to original.  It seems to be a popular size.  A 60 series tire will have a little more side wall flex than a 50 series - but perhaps a smoother ride. Same size tire front and rear will allow you to rotate tires - as rear often wear on inside due to lowering).  Spacers can be used to push tire out of wheel well if that is desired.

I like https://www.miata.net/cgi-bin/tirescgi for comparing tire size impacts

Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
165/80-15         5.2in  12.7in    25.4in         79.8in        794        0.0%
225/60-15         5.3in  12.8in    25.6in         80.5in        787        0.9%
Last edited by WOLFGANG
Gordon Nichols posted:

I have a CMC widebody with original Fuchs from a Porsche 911.  The suspension is IRS, not swing-arm with 3/4" anti-sway bars front and rear.

I have had 16" wheels on it since day one.  Earlier, I ran 6" wide rims on the front with 205X50 tires, and 7" wide on the rear with 225X50 tires.  That's a lotta tire on te ground!  The 205X50's on the front duplicates the outer tire diameter of the earlier VWs and leaves you with a speedo that's off by about 5% - 8% on the VDO replica speedos.  That wheel/tire combination was dynamite for handling - Best handling package I have ever had.  You will have to run wheel spacer/adapters to get the wheels out into the wheel well - I have 1-1/8" thick ones all around, made of Billet Aluminum and bought from Pelican Parts.  They're about $125 each and worth it.  they custom make them to whatever thickness you need.

Originally, I had Continental tires (don't remember the model) which had stiffer sidewalls.  After 12 years of running that combo, I traded my rear wheels for a pair of 6" Fuchs and now run 205's all around (Michelin).  I am also older and no longer corner as hard as I used to, so I have yet to feel the rear start to let go and never got it to let go even when pushed really hard with the 225's back there.

Hope this helps.  gn   They look cool, too!

IMG_2741

Thats my Same color and that looks so nice. Thanks for the help as it did help a lot. Get out and drive and thanks

Gordon Nichols posted:

I have a CMC widebody with original Fuchs from a Porsche 911.  The suspension is IRS, not swing-arm with 3/4" anti-sway bars front and rear.

I have had 16" wheels on it since day one.  Earlier, I ran 6" wide rims on the front with 205X50 tires, and 7" wide on the rear with 225X50 tires.  That's a lotta tire on te ground!  The 205X50's on the front duplicates the outer tire diameter of the earlier VWs and leaves you with a speedo that's off by about 5% - 8% on the VDO replica speedos.  That wheel/tire combination was dynamite for handling - Best handling package I have ever had.  You will have to run wheel spacer/adapters to get the wheels out into the wheel well - I have 1-1/8" thick ones all around, made of Billet Aluminum and bought from Pelican Parts.  They're about $125 each and worth it.  they custom make them to whatever thickness you need.

Originally, I had Continental tires (don't remember the model) which had stiffer sidewalls.  After 12 years of running that combo, I traded my rear wheels for a pair of 6" Fuchs and now run 205's all around (Michelin).  I am also older and no longer corner as hard as I used to, so I have yet to feel the rear start to let go and never got it to let go even when pushed really hard with the 225's back there.

Hope this helps.  gn   They look cool, too!

IMG_2741

You have 6” all the way around now? Why change from 6” front and 7” rear to 6” all the way around?

ALB posted:
Gordon Nichols posted:

Because now I can rotate the tires for even wear.  

Before, I was stuck with keeping the same tire in the same place all the time.

A small price to pay for better handling and just generally looking badass...

Rotating tires is for your daily driver.

With 6” on the front wheels, and 8” on the back, I can’t rotate my tires either.  But I like those fat tires for traction and stability.  Besides, the miles I put on each year mean the tires should be replaced due to old age, not wear.

Coyoteman356 posted:

For Porsche replica parts (speedster emblems, side curtains, mirrors, etc) who do you recommend purchasing such items from? Not going to believe it but a dog chewed my passenger side mirror (very upsetting). I live in Miami FL and have ordered from Vinatge speedsters in Cali as I was familiar with them back in the 90’s. Thanks

You can get parts from Vintage Soeedster Parts, Vintage Speedsters, Special Edition/Beck, Sierra Madre Collection, and Klasse 356. 

CoyoteDude:  The front steering has stops that prevent the front wheels from rubbing on the inner fender walls.  They are adjustable (for different size tires).  

Get it up on jackstands and find the pitman arm - a big arm on the bottom of the steering box that moves the tie rods back and forth.  There should be a couple of tabs on both sides of the arm that bump up against the movement limiters (those look like little bolts screwed into the frame with the heads hitting the Pitman arm at far left and right).

Adjust the limiters out a bit and you'll no longer rub.  Trial and error.

Gordon Nichols posted:

CoyoteDude:  The front steering has stops that prevent the front wheels from rubbing on the inner fender walls.  They are adjustable (for different size tires).  

Get it up on jackstands and find the pitman arm - a big arm on the bottom of the steering box that moves the tie rods back and forth.  There should be a couple of tabs on both sides of the arm that bump up against the movement limiters (those look like little bolts screwed into the frame with the heads hitting the Pitman arm at far left and right).

Adjust the limiters out a bit and you'll no longer rub.  Trial and error.

Dang. I had no idea and I’m the only owner of it and started it back in 1997 and gave to my Dad after his passing in 2016 it came back to me and I’ve forgotten alit about the build and never new that. Great info and everyone is very helpful. It’s awesome!

calmotion posted:

@Coyoteman356 you have 8 and 10 wow. You must have wide body  to fit that width. 

It rides rough though and steers a little tough but feels good on flat new blacktop there’s just not much of it around. I’m probably going to change the to 6 “ in front and 8” in rear and go from 15” to 16” as it’s been suggested on this post. I’ll probably keep the old steel wheels as they have some sentimental value. Man it’s awesome how everyone helps out here. What do you think about the 16” and going to 6” and 8”?

It rides rough - Well, that could be from stiff shocks, stiff torsion bar settings or stiff tire sidewalls.  For the shocks, get a set for a '67-'70 VW sedan, but stock oil-filled (not Gas) shocks.  That should help.  Look under the front beam to see if it has one or two torsion bar adjusters and report back.  We can help you depending on how many adjusters are under there.  Mess with those things before a wheel alignment.

16" wheel diameter is fine, although there is a whole encampment on here of 15" wheel people, but 16's are the bomb - the tires fill the wheel well so much better and your highway engine RPMs are slightly lower.

6" width is fine for most available tires.  8" in the rear, while certainly do-able, results in a tread width that is reeeeeaaaallllly wide on the ground - I'm assuming you'll be running something like a 245 or larger tire back there (and I think, at least with a CMC flared body, that you'll be limited to a 265 or smaller).  Not necessarily a bad thing, but remember that you'll have a LOT of rotating mass back there to move.  It's rotationally "heavier" so things like acceleration off the line will happen slower than if you were to have a smaller wheel/tire.  You'll also need a bit more "sauce" to make it move, like at least a built 2,110cc and preferably a 2332.  That's a lotta engine, there.  ($$$$)

My suggestion would be to keep it at a 7" X 16" in the rear with 225-245 rubber and you'll be fine.  Believe me - a 225 is a pretty wide tire when looking at it from the rear, and a 245 is really wide from back there!  what'cha gotta learn is how to move that wheel/tire mass!

Last edited by Gordon Nichols
Gordon Nichols posted:

It rides rough - Well, that could be from stiff shocks, stiff torsion bar settings or stiff tire sidewalls.  For the shocks, get a set for a '67-'70 VW sedan, but stock oil-filled (not Gas) shocks.  That should help.  Look under the front beam to see if it has one or two torsion bar adjusters and report back.  We can help you depending on how many adjusters are under there.  Mess with those things before a wheel alignment.

16" wheel diameter is fine, although there is a whole encampment on here of 15" wheel people, but 16's are the bomb - the tires fill the wheel well so much better and your highway engine RPMs are slightly lower.

6" width is fine for most available tires.  8" in the rear, while certainly do-able, results in a tread width that is reeeeeaaaallllly wide on the ground - I'm assuming you'll be running something like a 245 or larger tire back there (and I think, at least with a CMC flared body, that you'll be limited to a 265 or smaller).  Not necessarily a bad thing, but remember that you'll have a LOT of rotating mass back there to move.  It's rotationally "heavier" so things like acceleration off the line will happen slower than if you were to have a smaller wheel/tire.  You'll also need a bit more "sauce" to make it move, like at least a built 2,110cc and preferably a 2332.  That's a lotta engine, there.  ($$$$)

My suggestion would be to keep it at a 7" X 16" in the rear with 225-245 rubber and you'll be fine.  Believe me - a 225 is a pretty wide tire when looking at it from the rear, and a 245 is really wide from back there!  what'cha gotta learn is how to move that wheel/tire mass!

So 6 in front and 7 in rear and 16 inch. I think I’ll do that and then run a good set of tires?

Coyoteman356 posted:
Gordon Nichols posted:

It rides rough - Well, that could be from stiff shocks, stiff torsion bar settings or stiff tire sidewalls.  For the shocks, get a set for a '67-'70 VW sedan, but stock oil-filled (not Gas) shocks.  That should help.  Look under the front beam to see if it has one or two torsion bar adjusters and report back.  We can help you depending on how many adjusters are under there.  Mess with those things before a wheel alignment.

16" wheel diameter is fine, although there is a whole encampment on here of 15" wheel people, but 16's are the bomb - the tires fill the wheel well so much better and your highway engine RPMs are slightly lower.

6" width is fine for most available tires.  8" in the rear, while certainly do-able, results in a tread width that is reeeeeaaaallllly wide on the ground - I'm assuming you'll be running something like a 245 or larger tire back there (and I think, at least with a CMC flared body, that you'll be limited to a 265 or smaller).  Not necessarily a bad thing, but remember that you'll have a LOT of rotating mass back there to move.  It's rotationally "heavier" so things like acceleration off the line will happen slower than if you were to have a smaller wheel/tire.  You'll also need a bit more "sauce" to make it move, like at least a built 2,110cc and preferably a 2332.  That's a lotta engine, there.  ($$$$)

My suggestion would be to keep it at a 7" X 16" in the rear with 225-245 rubber and you'll be fine.  Believe me - a 225 is a pretty wide tire when looking at it from the rear, and a 245 is really wide from back there!  what'cha gotta learn is how to move that wheel/tire mass!

So 6 in front and 7 in rear and 16 inch. I think I’ll do that and then run a good set of tires?

Thanks

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