Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

Beginner Tire Recommendations

 
Post new topic   Reply to topic    924Board.org Forum Index -> 924 Racing Today
View previous topic :: View next topic  
Author Message
MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Tue May 15, 2018 1:10 pm    Post subject: Beginner Tire Recommendations Reply with quote

The car is finally beginning to come together. I need to get some tires for a beginner driver. I have both the 6" spiderwebs and 7" cookie cutters for wheels. I have fender flares rear and front and the coil overs have about 2-1/2" springs so fender and clearance shouldn't be an issue. I figure I need a pretty forgiving tire that lasts well and a couple or reports recommended a BFG Rival over the Toyo R888R or Kumho RS4. They will be used track only for vintage use. I will probably have about 140HP(10-1, mild port, 264 deg cam,MSDS) and weight of 2100b(guess). I figured on a tire size of 205/50 but could go to 225. I cannot legally go below the 50 section. I'm not even considering Hoosiers at this time.

Among the local vintage group Hoosiers are recognized fastest, the RS-4 good for longevity and some use Toyo's.

Which tires would be recommended?
_________________
Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
Back to top
View user's profile Send private message Visit poster's website
Cedric  



Joined: 27 Aug 2004
Posts: 2600
Location: Sweden

PostPosted: Tue May 15, 2018 9:20 pm    Post subject: Reply with quote

Is it for racing or just track days? For a track day NA i would stay on 205s on 7" wheels, i really like that setup, but all tyres are not the same width, even though they are sold as the same size.

All tyres i have been running have been very progressive on my cars, even aggressive compunds, though its a bit heavier than yours which of course affects the car response. My NA was very nice aswell, even with aggressive Rcomps. But of course, when stuff happens it happens at a higher speed level, which can get you into troubble. I didnt like the old R888s, way to sloppy sidewalls, couldnt handle heat that good aswell, but the R888r seemt to be much better at those points. What was nice with them though was the short warm up time, more aggressive tyres could be very sketchy until they reached a good heat level, the toyos were almost good from the start, not completely unimportant factor.

A more street oriented tyre will most likely be a bit more slippery at a lower limit, and thus making it easier to learn how to manage the traction in the best way. With that weight i think you will have quite some margin for tyre overheating and thus could chose tyre more freely, otherwise that is mostly the drive to have more tyre width.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/
Back to top
View user's profile Send private message MSN Messenger
924RACR  



Joined: 29 Jul 2001
Posts: 8794
Location: Royal Oak, MI, USA

PostPosted: Tue May 15, 2018 9:51 pm    Post subject: Reply with quote

Can't speak to those tire choices, since I'm only running on Ho-ho's, but size-wise I'd be inclined to use the 205's on the 6's, not 7's - save the weight/rotational inertia...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Cedric  



Joined: 27 Aug 2004
Posts: 2600
Location: Sweden

PostPosted: Wed May 16, 2018 3:29 am    Post subject: Reply with quote

I don't know if there is any weight differences between those wheels, the spider webs are no lightweights. The 7'' cookies are 6.9kg if i remember correctly, a really good track wheel.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/
Back to top
View user's profile Send private message MSN Messenger
924RACR  



Joined: 29 Jul 2001
Posts: 8794
Location: Royal Oak, MI, USA

PostPosted: Wed May 16, 2018 4:29 am    Post subject: Reply with quote

Even if they weighed the same, a 6" wide rim should have a little less rotational inertia due to less wheel flange.

But I'm pretty sure once upon a time I weighed them and confirmed they were lighter.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Cedric  



Joined: 27 Aug 2004
Posts: 2600
Location: Sweden

PostPosted: Wed May 16, 2018 4:49 am    Post subject: Reply with quote

924RACR wrote:
Even if they weighed the same, a 6" wide rim should have a little less rotational inertia due to less wheel flange.

But I'm pretty sure once upon a time I weighed them and confirmed they were lighter.



I guess it might be very dependent on what kind of tracks you drive on, ours are pretty short and twisty in general, thus quite hard on the tyres. But here the 7'' and 205 combination is by far the most common on cars with similar power to weight ratios like miatas, the reduced sloppyness and better tyre wear seems to outweigh the added inertia quite easily, but different tracks have different optimums.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/
Back to top
View user's profile Send private message MSN Messenger
MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Wed May 16, 2018 7:34 am    Post subject: Reply with quote

The car is track only although it might get a couple of illegal test drives if it can clear the driveway rocks. I weighed both wheels on bathroom balance scale and the cookie is about 3/4 lb lighter than the spiderweb. I think Ill probably go with the 205 Toyos on the 7" cookies as the increase in track should help a bit.
_________________
Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
Back to top
View user's profile Send private message Visit poster's website
winddude  



Joined: 15 Jan 2020
Posts: 61
Location: Vancouver Island

PostPosted: Wed Jul 22, 2020 7:25 am    Post subject: Reply with quote

are those on 15" or 16"s? I'm trying to figure out tire sizes for myself as well.
Back to top
View user's profile Send private message
MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Wed Jul 22, 2020 10:29 pm    Post subject: Reply with quote

I have 15"x7" cookie cutters. Tires I'm using are Nitto 01's 205/50/15. I'm still experimenting with tire pressure. I do not have a temperature gauge so shooting for about 34psi hot at this point. Last time out started at 26 cold and were 32 when hot so next time I start at 27psi. Maybe not the best way to do it, but best I can do for now. Our group is restricted to max of 50 section tires, I believe 924RACR is or was using 225/45's.
_________________
Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)
Back to top
View user's profile Send private message Visit poster's website
924RACR  



Joined: 29 Jul 2001
Posts: 8794
Location: Royal Oak, MI, USA

PostPosted: Wed Jul 22, 2020 10:40 pm    Post subject: Reply with quote

We were using 225/45/15 Hoosier R6s.

We, in ITB, are restricted not by tire size but by rim size, and so run 15x6s.

Yes, with 225 rubber - it can be done.

But we've since dropped back to 205/50/15 SM6 tires - used Spec Miata tires are a lot cheaper, and may be a touch faster on the larger tracks! (less rolling resistance)
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1353
Location: Washington DC area

PostPosted: Thu Jul 23, 2020 1:23 am    Post subject: Reply with quote

IT-B is allowed 7 inch rims now. I'm running 7 inch cookie cutters with the Miata Hoosiers (they are designed for a 7 inch rim). A very slight improvement over the 6 inch cookies. Also based on tire wear and temps, I run more camber on the left side of the car since most turns are right handers.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
Back to top
View user's profile Send private message
924RACR  



Joined: 29 Jul 2001
Posts: 8794
Location: Royal Oak, MI, USA

PostPosted: Thu Jul 23, 2020 2:27 am    Post subject: Reply with quote

Oh wow, that's weird, didn't notice that. I see that those are also switched up so you can run 225s with 6.0" rims, or 205s with 7.0" rims... goofy...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> 924 Racing Today All times are GMT + 10 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group