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Wheels and tires
Hello, I have placed my order for a complete MK4 kit. I am getting ready to make final changes and final payment this week. I’m having trouble deciding between “17 and “18 wheels. I like the look of the bigger ones but, if there is a big difference in ride quality I will gladly take the “17 wheels. If anyone has any experience with this, your input would be appreciated. Thanks.
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Steve >> aka: GoDadGo
Vince,
The taller the side wall of the tire the better the ride will be, but not all MK-4's are created equal.
15" tires, 235/60-15's and 295/50-15's will give you the most period correct look with the tallest sidewall possible; however, tire choice is limited.
Also, two of my pals have the 18" wheels on their cars while I'm running 17's but the car with the best ride quality has a very heavy 390 FE with the IRS set up.
Shown below is my car which sports a 3-Link rear end set up with 245/45-17's up front with 285/40-17's out back.
https://youtu.be/CaRlqMmKIzk
I chose this combination because this was the tallest of the 17" tires that I could run in an attempt to mimic the more period correct look of the 15" wheels.
Good Luck From The Dark Dart Side & I Hope This Helps!
Steve
Last edited by GoDadGo; 05-12-2019 at 08:31 PM.
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Thanks! I’ve been sure about every choice on this car so far. I’m just on the fence with this one thing. This car will have IRS and a small block 427. Great looking car by the way!
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Steve >> aka: GoDadGo
Originally Posted by
Vince C
Thanks! I’ve been sure about every choice on this car so far. I’m just on the fence with this one thing. This car will have IRS and a small block 427. Great looking car by the way!
Thanks for the complement.
Also, you can save a bunch of money on your engine because the 427 is way, way, way too much power for these cars.
The sweet spot is around 350 HP with torque figures in the same realm so you may want to reconsider the 427 inch engine.
For the record my 383 makes about 450 HP with similar torque figures and it will spin the tires at will in 1st, 2nd and 3rd.
This is with the rev-limiter set at a stupid low 4,300 RPM, but my operation range is between 2,000 and 6,300 RPM.
Good Luck & Take A Look At Edwardb's two MK-4 build threads because they will really help you.
SBF Build Solid Axle (5 Link) Thread:
https://thefactoryfiveforum.com/show...rogress-Update
Coyote IRS Build Thread:
https://thefactoryfiveforum.com/show...iversary-Build
His Work Is Phenomenal & He Truly Knows These Cars Better Than Most Of Us!
Last edited by GoDadGo; 05-12-2019 at 09:00 PM.
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Senior Member
GoDadGo (Steve) thanks for the shout-out. Again. Those threads just keep on giving.
Vince C I've had builds with 17-inch wheels and Nitto 555's and 18-inch wheels with Goodrich Rival's. I can honestly say there was little/no difference that I could attribute to the tires. The one with the 18's (#8674 Anniversary build) has the better ride. But it's also the one with IRS. Which is what I attribute the difference to. Note everyone will agree with me. But based on my experience with both, I wouldn't make a wheel choice between these two over ride concerns alone. I'm saying you probably wouldn't tell the difference. Other factors to consider? Today there are more 17-inch tire choices than 18-inch. And what 18's are out there cost more. But based on the industry, where bigger wheels are the norm, don't expect it will always be that way. Also depends on your brake selections and what wheels those fit. Also depends on your personal taste. The 18's do look slightly bigger. But it's very subtle and unless you had to two next too each other, you probably wouldn't notice that difference.
Build 1: Mk3 Roadster #5125. Sold 11/08/2014.
Build 2: Mk4 Roadster #7750. Sold 04/10/2017.
Build Thread
Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020.
Build Thread and
Video.
Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020.
Build Thread and
Video
Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023.
Build Thread. Sold 11/9/2023.
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Vince,
It may be beneficial to research tire makes, models and sizes prior to ordering or committing to a wheel. Not all tire versions are available in all sizes. Deciding on how you'll use the car may guide you towards one style/brand over another.
As EdwardB indicated there probably isn't a great difference in ride quality between the 17 & 18s once you get the air pressure set right (mid 20s to start). I'm a fan of larger rear tires, 315s are popular but not available in all versions. My plan is for 335s but it may take a few custom touches.
But I tend to disagree with GoDadGo on HP/Torque. I've run a 427W at 440 RWHP and think it's about right. I'm planning on the same engine for my current build with a power increase and less weight than my previous cars. But I make no claims to being "normal". Learn how the skinny pedal works.
Always happy to help another 427W brother and welcome to the site.
Jim
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Great, thanks you guys for the advice. I’m leaning towards the bigger wheels. That could change by tomorrow though.
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Steve >> aka: GoDadGo
The cool part of this forum is that all opinions are welcome so Jim probably likes going faster than me, likely a lot faster.
What ever engine you choose will be great, just know that banker in me tries to save money every where possible and 427's can get expensive. Also, remember to take into account your rear end and transmission gearing since this will have a lot to do with your ability to spin the rear wheels.
550 Torq X 3.23 Rear = 1776.50
476 Torq X 3.73 Rear = 1776.48
With that said you may want to consider going with the soft tire compound (100 - 200 Tread Wear) if you are going to go with a big inch engine. In addition, consider setting up a little spread sheet to make sure that your final gearing is where you'd like to be at whether you are cruising down the highway or at big end of the drag strip. I'm geared for 6,000 RPM at 124.42 MPH in 4th gear or 1,700 RPM at 70.51 MPH in 6th.
Good Luck From The Dark O.C.D. Side!
Last edited by GoDadGo; 05-13-2019 at 10:24 AM.
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Originally Posted by
GoDadGo
550 Torq X 3.23 Rear = 1776.50
476 Torq X 3.73 Rear = 1776.48
You do realize that you're eating all that gain up in friction losses with the majority of that being heat generated in the rearend in fourth gear (1:1 4th "gear" lockup on *most* common transmissions)?
And in 3rd gear you're actually putting less HP+ TQ to the ground than in 4th (with those additional frictional losses generating heat in the transmission)?
Just food for thought or discussion.
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Steve >> aka: GoDadGo
Originally Posted by
mike223
You do realize that you're eating all that gain up in friction losses with the majority of that being heat generated in the rearend in fourth gear (1:1 4th "gear" lockup on *most* common transmissions)?
And in 3rd gear you're actually putting less HP+ TQ to the ground than in 4th (with those additional frictional losses generating heat in the transmission)?
Just food for thought or discussion.
Mike,
I was trying to illustrate the of torque multiplication effect between the 3.23 and 3.73 rear end ratios.
Steve
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Senior Member
Ride quality is kind of personal. What is good for me might be harsh/soft, pick one, for you. In my case my wife, 75 years old, has no issues riding in the COBRA. Stock FFR coil overs, TKO-600, 3 link - 3:55 rear, 17" NITTO 555R 245X45X17 & 315X35X17 @ 21/22PSI 3-7/8" ride height. Ending useful life. will replace with NITTO NT01 255X40X17 & 315X35X17.
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Whats the widest tire you can do on the rear if you go with the 17" rims?
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Correct math on torque x gear.
Just rambling here..
850hp with 3.73 gears with 18" Kumho 285/30-18 and winning Goodguys in AutoX ... The car was CSX 3170.
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Originally Posted by
Jcdata
Correct math on torque x gear.
Just rambling here..
850hp with 3.73 gears with 18" Kumho 285/30-18 and winning Goodguys in AutoX ... The car was CSX 3170.
Welcome to a driver or owner of the SCCA SOLO National Championship CAM-S car of 2015.
Page 56 here:
https://dk1xgl0d43mu1.cloudfront.net...pdf?1444922039
I'm certain I'd like to hear more.
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Senior Member
Originally Posted by
Drezx6r
Whats the widest tire you can do on the rear if you go with the 17" rims?
Not really sure of the widest.... but the 315/35r17 that FFR recommends and sells as a package is actually one wide tire!
My M3 with competition package only has 265’s in the back. 2018 Vette Z51 package only (lol only?) has 285’s The new 2019 Vette has 335’s. Those are huge, and only 20mm (roughly 3/4”) wider than FFR 315’s
Just my 2¢
Kurt
If everything seems under control, you’re just not going fast enough....
Build thread
MKIV complete kit # 9395 delivered 7/31/18
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Senior Member
What SSNK4US said about 315X35X17:
The floor tiles are 12"X12". That's about 2 feet of tire rubber side to side. Good fit no rubbing on standard FFR suspension components & wheels. Tires are inside the wheel wells at the top.
Last edited by BEAR-AvHistory; 05-14-2019 at 09:05 AM.
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Originally Posted by
BEAR-AvHistory
What SSNK4US said about 315X35X17:
The floor tiles are 12"X12". That's about 2 feet of tire rubber side to side. Good fit no rubbing on standard FFR suspension components & wheels. Tires are inside the wheel wells at the top.
Originally Posted by
SSNK4US
Not really sure of the widest.... but the 315/35r17 that FFR recommends and sells as a package is actually one wide tire!
My M3 with competition package only has 265’s in the back. 2018 Vette Z51 package only (lol only?) has 285’s The new 2019 Vette has 335’s. Those are huge, and only 20mm (roughly 3/4”) wider than FFR 315’s
Just my 2¢
Kurt
thank you both, 315 looks great BEAR. I wish my 15 Stingray had wider.
Last edited by Drezx6r; 05-14-2019 at 06:24 PM.
Reason: grammer
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Great info, thanks everyone. I went with the 18”. The kit is ordered and payed for. Can’t wait to get started!
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Senior Member
Congrats Vince! Now the waiting game begins. Hopefully time will fly!
More details on your order? Building your own motor? Blueprint? Forte? Etc etc etc lol
Kurt
If everything seems under control, you’re just not going fast enough....
Build thread
MKIV complete kit # 9395 delivered 7/31/18
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I’d love to build my own motor, it’s just so hard to beat the crate motors. I ordered the complete kit with IRS and Wilwood brakes. It gets a heater for my wife. It will get a small block 427 and a Tremec 6 speed.
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Senior Member
Cool! Looking forward to hearing more when you get going.
Kurt
If everything seems under control, you’re just not going fast enough....
Build thread
MKIV complete kit # 9395 delivered 7/31/18
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Originally Posted by
Vince C
I’d love to build my own motor, it’s just so hard to beat the crate motors. I ordered the complete kit with IRS and Wilwood brakes. It gets a heater for my wife. It will get a small block 427 and a Tremec 6 speed.
Congratulations! I also did IRS along with the Wilwood Brakes. I am about a month away from being road legal. Everything about the car is seriously BA, enjoy it!
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Senior Member
Congrats.
The heater for your wife is a good idea no matter where you live. I am in Florida and use mine quite a bit. I also recommend heated seats. A lot of events, cruises, autocross, track days, etc require an early morning start. A heater makes a huge difference during those early morning runs in the winter. Also good for late night returns.