I have a 994s with BBS split rims from a 996 I believe 18" it has 245/40/18 is this tyre to high profile making the rolling circumference bigger ie higher geared and speedo in accuracy just wondered how this wheel / tyre combination compares to the original 15" or 16" wheels, the wheels are nice but I'm thinking I like the cookie cutters, might even consider straight swap with someone who wants the BBS wheels for excellent cookies.
Rolling circumference
- Thread starter Lance
- Start date
It's a fair way out.
Original fit was 195/65 15, against which you are running 2.86% higher gearing than standard (plus of course lots of extra rolling resistance and aerodynamic drag).
Judged purely in terms of rolling radius, a 255/35 18 is only 0.3% higher geared than standard, but then that's even more excessive in terms of width.
In 16", you would want either 205/55 16 or 225/50 16 - both are 0.35% lower geared than original rubber.
In 17", which is really as far as one ought to go on a 944, then it would be 205/50 17 (0.3% higher geared than standard) or 225/45 17 (no significant change from standard gearing).
If you can find someone who wants to swap with a nice set of 15" cookie-cutters I'd bite their arm off if I were you. The car will be vastly nicer to drive.
Original fit was 195/65 15, against which you are running 2.86% higher gearing than standard (plus of course lots of extra rolling resistance and aerodynamic drag).
Judged purely in terms of rolling radius, a 255/35 18 is only 0.3% higher geared than standard, but then that's even more excessive in terms of width.
In 16", you would want either 205/55 16 or 225/50 16 - both are 0.35% lower geared than original rubber.
In 17", which is really as far as one ought to go on a 944, then it would be 205/50 17 (0.3% higher geared than standard) or 225/45 17 (no significant change from standard gearing).
If you can find someone who wants to swap with a nice set of 15" cookie-cutters I'd bite their arm off if I were you. The car will be vastly nicer to drive.
Thank you for taking the time to explain in very good detail, funny enough the car feels quite sluggish 2.5 16v and acceleration is not what I would have expected, only 944 I have driven but I get what your saying about gearing, think I will move these wheels on and take your advise on 15" or 16" cookie cutters or Fuchs! Would be nice thanks
924nutter
PCGB Member
If you have the 2.5 16v then you may well think it is sluggisn below about 3,600 rpm, because the engine is not doing its best breathing below this. Get it to 3600 and it should feel like a small turbo coming on boost. It has a higher rev limit (6800) than the 8 valve engine. Porsche Produced this engine so that in the US they could offer a catalysed version whilst still maintaining something around 160 bhp. In the UK the engine produces 188 bhp, but it needs to be revved. I had one and I thought it was great, as I had just upgraded from a normally aspirated 924. You just had to be ready and in the right gear. The 944s, as opposed to the S2 has a reputation, some would say, undeservedly, of being the least torquey of the normally aspirated 2.5 litre engines. In the right circumstances I did see **7 on the speedo, but prudence prevails.
I love Cookies and Fuchs but they wont easily fit an S as the offsets will be too smalland the tyres will foul the archs.
So i cant fit cookies to my car? not even with lower profile tyres? That's a shame, what wheels can I fit then? I thought all 944 were the same ( forgive my ignorance new to ownership) what offset am I looking at? My car came with genuine 18" bbs splits from a carrera 996 I think, I know these wheels go for around £700 a set, I'm not bothered about the money difference im happy to swap for a decent set of correct wheels if anyone is interested
924nutter
PCGB Member
There are two ranges of offset, one for non abs and the other for abs. The offset is counter-intuitive in that the more offset the further IN the wheel will sit. Typical values are 23mm for non abs and 52 for abs, so if you fit abs wheels to an early car the inner rims can rub depending on rim witdh. Note these are typical values and refer how far the mounting flange is offset inwards from an imaginary zero datum. Riule of thumb; wider rim more offset to get the outer edge back under the wheel arch with the rubbing of the inner rim as a limit on width and offset, so if your S has abs then cookie cutters have the offset in the lower range and will stick out miles by comparison. (in a nutshell)
By the way Lance we are sure you mean that you have a 944S and not a 994S, but as a newbie we'll let you off, lol
By the way Lance we are sure you mean that you have a 944S and not a 994S, but as a newbie we'll let you off, lol
Wheel wise if you want 16" or 15" you will be looking at D90 or tele dails.
Personally my advice would be pick up a set cheap ish, try them out and if u think there nicer sell the 18"
Your tire size on 18" should be 225/40/18" front and 255/35/18"
Rear
This won't put your speedo out my much
15" Tele dails would be the correct wheels from factory
I had an S and ran 18" wheels drove an S2 which should only have 20 more bhp and it felt much quicker lower down, thought it could be the wheels, so I changed them 993 winter cups 16" 5 spoke. Quite a light wheel much lighter then 18" but didn't really notice a huge impovement.
Same with my turbo, had 18" on put my 16" cs on and didn't notice from drivers seat the differnce, actually forgot I had changed them
Personally my advice would be pick up a set cheap ish, try them out and if u think there nicer sell the 18"
Your tire size on 18" should be 225/40/18" front and 255/35/18"
Rear
This won't put your speedo out my much
15" Tele dails would be the correct wheels from factory
I had an S and ran 18" wheels drove an S2 which should only have 20 more bhp and it felt much quicker lower down, thought it could be the wheels, so I changed them 993 winter cups 16" 5 spoke. Quite a light wheel much lighter then 18" but didn't really notice a huge impovement.
Same with my turbo, had 18" on put my 16" cs on and didn't notice from drivers seat the differnce, actually forgot I had changed them
I understand the offset issue and my car does not have abs, in response to T3rra you state you felt no difference, I assume this is because you went from 18" with correct tyre profile to 16" with correct tyre profile making the rolling circumference the same if not only marginally different. I figure my best solution then is to fit 255 35 18 tyres at the back! This should in theory reduce the gearing and noticeably an improvement in acceleration or am I talking out of my.....
Yes, my 1st set off 18" wheels, which I brought mainly for the tires turn out that the rears where one profile step 2 high. 265/40/18 and caused rubbing issues at about 3 o o'clock on the wheel arch.
18" tires can get expensive. Depends on what sort off look / style you want for your car.
Stock turbo has 225 front and 245 rear
225 up front will make steering slightly heavier them 215, in theory 18" wheels will give a harsher ride and are not reccommend retro fit by Porsche. But many people run them.
If you don't mind part worns you can try the correct size.
I found with my S if you going 2 floor it then u need 2 from the off. 1st and 2nd up 2 red line this way when u change up your in the power band
18" tires can get expensive. Depends on what sort off look / style you want for your car.
Stock turbo has 225 front and 245 rear
225 up front will make steering slightly heavier them 215, in theory 18" wheels will give a harsher ride and are not reccommend retro fit by Porsche. But many people run them.
If you don't mind part worns you can try the correct size.
I found with my S if you going 2 floor it then u need 2 from the off. 1st and 2nd up 2 red line this way when u change up your in the power band
924nutter
PCGB Member
Welll I didn't want to stick my neck out as it was 20 years ago but I didn't recall mine having abs. That being the case see if you can borrow a cookie cutter and offer it up to see what it looks like, just incase yours has the abs hubs without the system, after all it is an oval dash isn't it? Infact I will hve a gander at PET and see if I can see what's what.
924nutter
PCGB Member
I doubt whether you will notice any improvement; Lowering the gearing by the roling radius is the same as being in a lower gear. The S engine needs to be kept on the boil, you should manage the use of the box of cogs to do that or you will be woefully short of cruising range and it would be like driving in fourth with comensurate engine noise and loss of economy, if you are to positively effect the way the car pulls in any meaningfull way, in my considered opinion. Rev the blighter. It will do 101 in third at max revs so if you're doing 60 on the motorway and you want to boot it drop it down two cogs, and floor it, she'll fly then. Keep the revs up and you can squeal the tyres from 2nd to third if you ace the change. Back in its day my S was a match for that Japanese v-tec stuff. I remember a chap in a blue Honda Civic LSI got a very close up view of my number-plate, enlarging in his mirrors, when he thought he would cut in front of me and pull away. What fun we had exchanging gestures when he finally puuled in out of the way.I say this next bit tongue in cheek because this is a standing joke and banter between the S2 and Turbo owners. If you want to potter like an old man, get an S2 with auto. Messrs Porsche have provided a handy stick like object that protrudes out of the central backbone. In the S it needs to be stirred like you are trying to recombine cream that is on the turn, in a cup of coffee lol. Don't forget that pre S2 the S was the most powerfull normally apsiprated 944, and had the engine not been enlarged to 3.0 we would not be deriding the 944S' lack of useable torque below 3000 revs, so when all said and done it is not a bad car, and lag considered, not a whole lot slower than the 220 turbo.
An appaling peice of driving by me true, but on the way to Guildford to have a Porsche immobiliser fitted, I saw a gentleman in a pug 1.9 gti making good progress but his error was to cut my Mrs up on entry to a roundabout. exiting the roundabout I kept the S in second so had about 4,000 revs on. When he tried to queue jump me and barge-in in front I floored it and he ended up overtaking a space in the road where I had been, as I was about 200 yds down he road. That's how well the S can go but did I happen to mention you need to rev it. Not really meaning to lecture but the S really is a different kettle of fish to the torquey 8 valve, and does require a slightly more racy style to your driving if it is no going to "bog". I will agree that in fifth a spiritedly driven Robin Reliant would pull away at motorway speeds; oh no wait, a Robin wont do 70 will it? How about a Skoda Estelle then. Sorry if I went on a bit.
An appaling peice of driving by me true, but on the way to Guildford to have a Porsche immobiliser fitted, I saw a gentleman in a pug 1.9 gti making good progress but his error was to cut my Mrs up on entry to a roundabout. exiting the roundabout I kept the S in second so had about 4,000 revs on. When he tried to queue jump me and barge-in in front I floored it and he ended up overtaking a space in the road where I had been, as I was about 200 yds down he road. That's how well the S can go but did I happen to mention you need to rev it. Not really meaning to lecture but the S really is a different kettle of fish to the torquey 8 valve, and does require a slightly more racy style to your driving if it is no going to "bog". I will agree that in fifth a spiritedly driven Robin Reliant would pull away at motorway speeds; oh no wait, a Robin wont do 70 will it? How about a Skoda Estelle then. Sorry if I went on a bit.
Liking your post and being a chap in his mid ok late forties I grew up with golf gti 16v's so driving on the red line was where I was comfortable, I have not had the car long only a month, my first 944 I was looking for just a 2.5 lux because I want to use it daily but came across an immaculate black ventiler which although done 156k its just had a full rebuild and only covered 9k miles so still running it in really but will drive it harder as time goes on might go out later for a blast!
Early cars up to and including 1986 model year, had the 23mm offset wheels (15x7" rims Cookies , Fuchs or "deepdish" telies) and dont have the facility for ABS.
All later cars (inc your S) have the larger hubs which can have ABS although it was not standard till '89 or '90 and these cars need 52mm ish offset wheels. This is only a guide because 7" 7.5" 8" and 9" rims where all fitted to different models and the width has an effect on the offset required.
All later cars (inc your S) have the larger hubs which can have ABS although it was not standard till '89 or '90 and these cars need 52mm ish offset wheels. This is only a guide because 7" 7.5" 8" and 9" rims where all fitted to different models and the width has an effect on the offset required.
944 man
Active member
The silly making of Ventiller into a name really get on my tits. *nods*
All 1987 model year onwards cars are 'ABS cars' whether they actually had the expensive option fitted or not. 23.3mm offset wheels may well fit onto the car (actually, I know that 7" wheels will fit), but they wont fit properly and the car wont handle or steer as it should. The car will be dangerous in the even of a puncture too.
All 1987 model year onwards cars are 'ABS cars' whether they actually had the expensive option fitted or not. 23.3mm offset wheels may well fit onto the car (actually, I know that 7" wheels will fit), but they wont fit properly and the car wont handle or steer as it should. The car will be dangerous in the even of a puncture too.
924nutter
PCGB Member
I had a poke around the forum and found this in FAQ with thanks to Paul Smith and Lord Nulters of Rickmansworth A412 and bar;
"Because of the confusion that model year and year of registration cause, then Id suggest going by the age identifier in the VIN. WPOzzz94zFN4xxxxx and before will use ET 23mm wheels whereas WPOzzz94zGN4xxxxx and later wheels will suit ET 52.3mm wheels".
WPO Is W (Germany ) and PO (Porsche) zzz are character spaces. These are followed by 94 the first two model type digits. The next z is a spare chacter then comes the year letter (A=1980, up to year 2001, when the year digit was introduced again (1= 2001) next is N for Neckersulm the Audi plant where very nearly all FOUR CYLINDER front engine cars were built or S for Stuttgart build, (Racing homologation variants of the 924 were built in Stuttgart) then comes the third model type digit (4) the last five digits are the unique number that identifies the rolling shell.
For example, A 928 S4 would look like WPOzzz92zHS8xxxxx.
"Because of the confusion that model year and year of registration cause, then Id suggest going by the age identifier in the VIN. WPOzzz94zFN4xxxxx and before will use ET 23mm wheels whereas WPOzzz94zGN4xxxxx and later wheels will suit ET 52.3mm wheels".
WPO Is W (Germany ) and PO (Porsche) zzz are character spaces. These are followed by 94 the first two model type digits. The next z is a spare chacter then comes the year letter (A=1980, up to year 2001, when the year digit was introduced again (1= 2001) next is N for Neckersulm the Audi plant where very nearly all FOUR CYLINDER front engine cars were built or S for Stuttgart build, (Racing homologation variants of the 924 were built in Stuttgart) then comes the third model type digit (4) the last five digits are the unique number that identifies the rolling shell.
For example, A 928 S4 would look like WPOzzz92zHS8xxxxx.
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