Cosmis or RPF1
02-22-16, 11:45 AM
#1
Cosmis or RPF1
Hello All,
I am really torn and not sure which wheel I want to run on my FD. On one hand, I want a concave wheel that I have not seen run before, and on another I want a lightwight wheel. Price of the Cosmis R1 and Enkei RPF1 are pretty close, with the Cosmis being about $100 cheaper.
Specs are:
Cosmis R1 18×10.5 +30mm 5×114.3 roughly 22lbs (unofficial, one source)
RPF1 18x10 et +38 5x114.3 roughly 19lbs
Will the weight difference be noticeable? I would probably have to run staggered on the Cosmis wheels with 18x10.5 and 18x9.5 due to offsets but I really don't mind. I don't track the car nor are there any places around here to do it at. Any help or insight would be great. I know it comes down to being my decision but sometimes I like input.
I am really torn and not sure which wheel I want to run on my FD. On one hand, I want a concave wheel that I have not seen run before, and on another I want a lightwight wheel. Price of the Cosmis R1 and Enkei RPF1 are pretty close, with the Cosmis being about $100 cheaper.
Specs are:
Cosmis R1 18×10.5 +30mm 5×114.3 roughly 22lbs (unofficial, one source)
RPF1 18x10 et +38 5x114.3 roughly 19lbs
Will the weight difference be noticeable? I would probably have to run staggered on the Cosmis wheels with 18x10.5 and 18x9.5 due to offsets but I really don't mind. I don't track the car nor are there any places around here to do it at. Any help or insight would be great. I know it comes down to being my decision but sometimes I like input.
02-22-16, 11:24 PM
#3
thanks for the feedback. There is a local guy selling a pair of 18x9.5 et15 RPF1's cheap so i will be test fitting them this weekend. They are not ideal but the deal I can't pass up if they fit okay. If it works out I will pick up a set of rears from a vendor and save a few hundred. We shall see.
Maybe you are right, maybe RPF1's are the right call but they're so boring and everyone has them that it is pushing me away. If the test fit goes well and I can save enough money I will go for them.
Maybe you are right, maybe RPF1's are the right call but they're so boring and everyone has them that it is pushing me away. If the test fit goes well and I can save enough money I will go for them.
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02-24-16, 06:03 AM
#9
Senior Member
Tire and wheel weight and width do affect handling feel off the track. I prefer relatively smaller and lighter wheels and tires, particularly the fronts which have a greater impact on handling feel. You might consider staggering front/rear. The effect on handling balance on the street is pretty much nonexistent.
I don't think big/wide wheels do much positive for handling on a street car. In addition to greater weight and more tramlining, 275 -295 width tires will be stone cold for 99.9% of street usage on a sub-3000 lb. car and not in their optimal temp range for grip. More ultimate lateral grip once warmed up, but they'll almost never (if ever) get there on the street. IMO, better off in the 225-255 width range for real-world street grip. (Of course choosing the best compound for usage envelope is the most critical thing!)
I don't think big/wide wheels do much positive for handling on a street car. In addition to greater weight and more tramlining, 275 -295 width tires will be stone cold for 99.9% of street usage on a sub-3000 lb. car and not in their optimal temp range for grip. More ultimate lateral grip once warmed up, but they'll almost never (if ever) get there on the street. IMO, better off in the 225-255 width range for real-world street grip. (Of course choosing the best compound for usage envelope is the most critical thing!)
Last edited by ZDan; 02-24-16 at 06:48 AM.
02-24-16, 12:44 PM
#10
Tire and wheel weight and width do affect handling feel off the track. I prefer relatively smaller and lighter wheels and tires, particularly the fronts which have a greater impact on handling feel. You might consider staggering front/rear. The effect on handling balance on the street is pretty much nonexistent.
I don't think big/wide wheels do much positive for handling on a street car. In addition to greater weight and more tramlining, 275 -295 width tires will be stone cold for 99.9% of street usage on a sub-3000 lb. car and not in their optimal temp range for grip. More ultimate lateral grip once warmed up, but they'll almost never (if ever) get there on the street. IMO, better off in the 225-255 width range for real-world street grip. (Of course choosing the best compound for usage envelope is the most critical thing!)
I don't think big/wide wheels do much positive for handling on a street car. In addition to greater weight and more tramlining, 275 -295 width tires will be stone cold for 99.9% of street usage on a sub-3000 lb. car and not in their optimal temp range for grip. More ultimate lateral grip once warmed up, but they'll almost never (if ever) get there on the street. IMO, better off in the 225-255 width range for real-world street grip. (Of course choosing the best compound for usage envelope is the most critical thing!)
02-25-16, 07:23 PM
#13
found a deal on the 9.5 +35 so I ordered two in hyper bronze. I will be going for an aggressive fitment, and have the eastwood fender roller to roll and pull the fenders if need be. I will test these on the front and rear, if I think I can pull 10.5 in the rear I will. I will update with pics in a week or two when I get the coilovers installed.
02-27-16, 07:37 AM
#14
Hello All,
I am really torn and not sure which wheel I want to run on my FD. On one hand, I want a concave wheel that I have not seen run before, and on another I want a lightwight wheel. Price of the Cosmis R1 and Enkei RPF1 are pretty close, with the Cosmis being about $100 cheaper.
Specs are:
Cosmis R1 18×10.5 +30mm 5×114.3 roughly 22lbs (unofficial, one source)
RPF1 18x10 et +38 5x114.3 roughly 19lbs
Will the weight difference be noticeable? I would probably have to run staggered on the Cosmis wheels with 18x10.5 and 18x9.5 due to offsets but I really don't mind. I don't track the car nor are there any places around here to do it at. Any help or insight would be great. I know it comes down to being my decision but sometimes I like input.
I am really torn and not sure which wheel I want to run on my FD. On one hand, I want a concave wheel that I have not seen run before, and on another I want a lightwight wheel. Price of the Cosmis R1 and Enkei RPF1 are pretty close, with the Cosmis being about $100 cheaper.
Specs are:
Cosmis R1 18×10.5 +30mm 5×114.3 roughly 22lbs (unofficial, one source)
RPF1 18x10 et +38 5x114.3 roughly 19lbs
Will the weight difference be noticeable? I would probably have to run staggered on the Cosmis wheels with 18x10.5 and 18x9.5 due to offsets but I really don't mind. I don't track the car nor are there any places around here to do it at. Any help or insight would be great. I know it comes down to being my decision but sometimes I like input.
Lime Rock Park, CT
Thompson Speedway Motorsports Park, CT
New Hampshire Motor Speedway, NH
Club Motorsports, NH
Thunder Road Raceway, VT
Palmer Motorsports Park, MA
Just to name a few....
02-27-16, 10:33 PM
#15
I knew of Lime Rock Park and the strip in NH. Maybe I should rephrase, I don't foresee myself making it there anytime soon so I would rather go with a set that will I will be okay with and enjoy looking at when I take it out for drives. It will be driven several times a week so that will happen much more often than time at a track.
02-28-16, 04:50 AM
#16
Senior Member
New Hampshire Motor Speedway is not a "strip"! It's a road course that goes outside the oval speedway. Kind of a tight "Miata" track, but fun and includes elevation changes.
If you're worried at all about unsprung and rotational mass and handling feel on the street, I think 18x9.5 F /18x10.5 R are on the big-and-heavy side for a 2800 lb. FD. Obviously others feel differently...
If you're worried at all about unsprung and rotational mass and handling feel on the street, I think 18x9.5 F /18x10.5 R are on the big-and-heavy side for a 2800 lb. FD. Obviously others feel differently...
02-28-16, 08:24 PM
#17
Official weights were ~3lbs heavier than the rpf1's which really isn't much. Not enough for me to use that as the definitive answer to my questions so I went with what I found to be more cosmetically appealing. RPF1s are a tried and true wheel but I wanted something different. I am test fitting the 9.5 and will go from there. If I go a different route and start hitting a track more then I will refocus my wheel and coilover choice.
02-28-16, 10:10 PM
#19
. With a baby on the way, I think I will just be happy to get the FD out as much as I can, even if it's to go pick up formula 
04-06-16, 09:33 AM
#22
Well I got the wheels fit and on for "summer" however it has since snowed and the coolant seals in the motor went so it is at the show for a rebuild. I rolled the fenders using the eastwood fender roller so there isn't a lip or anything. I purchased a used set of coilovers and didnt like how they made the car sit. I guess the PO ran them without the factory top hats, so I am now running a 5 inch swift spring in 16kg. The car is pretty low but doesn't scrape and the wheels tuck nicely. I will update with pics once I get the car back.
03-08-18, 05:39 PM
#24
wow it's been a while. I had the cosmos r1's for a season then decided to go with feed style over fenders and 18x10.5 et15 rpf1's. These will stay while I look for a set of 3 piece wheels. I'll update the thread once I choose a vinyl wrap color and get it all done!
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