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dreamgts
Joined: 29 Dec 2009
Posts: 504
Location: malta
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 Posted: Mon May 23, 2011 7:45 am Post subject: Tyres & Sizes |
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I have these set of 16inch rims which I originaly bought for a Ford Cortina Mk 1. They are 16inch x 7. 108 x 4.
http://s1081.photobucket.com/albums/j349/iqssm/?action=view¤t=SP_A0043.jpg
I was thinking to place them on the webbered Porsche which I just purchased (minlites look better on the Cortina) since they have been laying around now for a few weeks.
It seems though that in order to keep to the circumference of the original 14inch tyre I cannot exceed the circumference by more than 3% according to a tyre manufacturer.
Therefore the closest i got was either 235 x 40 x 16(+2.83%) or 225 x 40 x 16(+1.48%), 40 being the profile.
I am familiar with 40 profile tyres and these seem to be quite low and close to the rim. yet my main concern would be if these low profile tyres would affect the handling of the car. Althouhg the tyre sizes are quite wide being 225 and /or 235 which would aid in cornering, grip etc Im still concerned about the profile.
Does anyone have any experience with low profile tryes for track use. Does the width compensate for this. Shall I have to use any type of spacers for the rims to fit.???? Any risk of the tyres rubbing with anything?
Thanks
dreamgts
_________________
2 PORSCHE 924 (CURRENT PROJECTS)
2 CLASSIC CORTINAS (FINISHED)
1 CLASSIC FIAT(FINISHED)
1 CLASSIC FIAT 132 2000CC(JUST PURCHASED)
4 SUV'S
2 SEDANS
1 OPEL PANEL VAN
WIFES SUZUKI ALTO |
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Cedric
Joined: 27 Aug 2004
Posts: 2827
Location: Sweden
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| Posted: Mon May 23, 2011 4:40 pm Post subject: Re: Tyres & Sizes |
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| dreamgts wrote: | I have these set of 16inch rims which I originaly bought for a Ford Cortina Mk 1. They are 16inch x 7. 108 x 4.
http://s1081.photobucket.com/albums/j349/iqssm/?action=view¤t=SP_A0043.jpg
I was thinking to place them on the webbered Porsche which I just purchased (minlites look better on the Cortina) since they have been laying around now for a few weeks.
It seems though that in order to keep to the circumference of the original 14inch tyre I cannot exceed the circumference by more than 3% according to a tyre manufacturer.
Therefore the closest i got was either 235 x 40 x 16(+2.83%) or 225 x 40 x 16(+1.48%), 40 being the profile.
I am familiar with 40 profile tyres and these seem to be quite low and close to the rim. yet my main concern would be if these low profile tyres would affect the handling of the car. Althouhg the tyre sizes are quite wide being 225 and /or 235 which would aid in cornering, grip etc Im still concerned about the profile.
Does anyone have any experience with low profile tryes for track use. Does the width compensate for this. Shall I have to use any type of spacers for the rims to fit.???? Any risk of the tyres rubbing with anything?
Thanks
dreamgts |
The available space is all about ET, the wheels above seems to be high ET and might sit to far inwards and thus hitting against the spring and/or inside of the body at the rear.
Why do you care about total diamter on track wheels, get it as low as possible to gear down the car. The only "concern" is that the speedo will show a different value.
Width depends on what tyres you will use, on r-compund i wouldnt want to go wider than 205, thats my experience. But i have a bit heavier car probably. It could work with 225 street tyres, but it depends on how fast you aim to drive and what tyres.
Low profile can give you more speed on the track, but they are in general more sensitive to wheel alignment, bad alignment shows in wear much faster than on more tolerant high profile tyres. Lower profile and stiffer sidewall (in for example r tyres) gives a better fell for the car when you run at full speed but can give you a sligthly less forgivness at the limit, but thats not extreme in any way.
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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dreamgts
Joined: 29 Dec 2009
Posts: 504
Location: malta
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| Posted: Mon May 23, 2011 6:25 pm Post subject: |
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Hi Cedric, saying that the tyres/rims will hit something at the rea means that I have to fit spacers then right?
Actually Im trying to go as low as possible and I thought maybe that 40 profile tyres would do perfectly.
My aim is to get as much grip as possible with wide low profile tyres without disrupting the overall diameter of the original tyre size. It seems that low profile tyres might do the job.
Im going to have a look at Firestone, Bridgestone Dunlop and Toyos when I have some free time this week, So I will also have to see to it that the tyre walls are stiff too right? I intend to do some testing with this car for the D prod project besides tracking it, so what works well on this car will go on the D Prod project too.
thanks
dreamgts
_________________
2 PORSCHE 924 (CURRENT PROJECTS)
2 CLASSIC CORTINAS (FINISHED)
1 CLASSIC FIAT(FINISHED)
1 CLASSIC FIAT 132 2000CC(JUST PURCHASED)
4 SUV'S
2 SEDANS
1 OPEL PANEL VAN
WIFES SUZUKI ALTO |
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| Back to top |
|
|
Cedric
Joined: 27 Aug 2004
Posts: 2827
Location: Sweden
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| Posted: Mon May 23, 2011 8:29 pm Post subject: |
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| dreamgts wrote: | Hi Cedric, saying that the tyres/rims will hit something at the rea means that I have to fit spacers then right?
Actually Im trying to go as low as possible and I thought maybe that 40 profile tyres would do perfectly.
My aim is to get as much grip as possible with wide low profile tyres without disrupting the overall diameter of the original tyre size. It seems that low profile tyres might do the job.
Im going to have a look at Firestone, Bridgestone Dunlop and Toyos when I have some free time this week, So I will also have to see to it that the tyre walls are stiff too right? I intend to do some testing with this car for the D prod project besides tracking it, so what works well on this car will go on the D Prod project too.
thanks
dreamgts |
Yes, you might need spacers, if you can measure or read ET its easier to give a first opinion. I have tried several wheels and racier camber angles can make wheels fit that shouldnt and make other wheels collide. for 7" wheels and camber angles about -2 degrees will probablt need ET 35 or something like that to cleare the springs. If you cut the springs seats and installa djustable spring seats from for example rallydesign.co.uk you will have far more flexibility in wheel placement.
Go as low as you can buy, small diamter wheels gives lower gearing, that makes some noticable improvement on acceleration compared to higher ones, especially on cars with less power. Harder to notice on my turbo compared to the n/a.
When it comes to track day tyres i have tried toyo r888, bridgestone 540, hankook z211 and michelin pilot sport cup on my cars, except for variuos street tyres which mostly were junk. I also have tried tr1 on a endurance racing 924 and they worked pretty good for being a street tyre, but the car was ligth( about 1000kg).
The MPSC is easily the tyre of my choice (bought a mountain of used tyres or else they are bloody expensive), best designed sidewall and overall a nice tyre. R888 was cheap but melted down when you drove hard and got a bit sloppy in the sidewall when they got hot. The bridgestones were super in all aspects except for noice and comfort but i dont think you can buy them anymore. z211 was more streetable but ok on the track, much less tracking on bad roads.
As for budget tyre i´ve heard good things about khumos tyre (v70, camskill.co.uk, at least in smaller diameters. But it wucks in wet where the r888 wins the round.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/ |
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