18" Tires

[Railroad]

Doing some tire shopping. I think I am close enough, they will not dry rot before I get it out of the barn.
I am considering Michelin Pilot Sport Cup 2, 245/40zr18 s on the front and
BFG G Force Rivals 315/30zr18 s on the rear.

I hope to have a sticky tire with enough tread to handle some water. I doubt being on the track, unless it is a controlled lap at Barber.
I have run Toyos and Nittos, but in much heavier autos.
,,glad to hear any advice.

[GFX2043mtu]

Don’t mix tires. Bad handling can occur and cause bad situations. There are a decent number of options for tires out there depending on your use. The BF Goodrich rivals are great for the street and some rain. Then you have the Falkin RT615k tires and the Toyo R888R’s but the Toyos are not meant for rain. Choose for your intended use and always remember the back getting loose is due to improper application of the right pedal. If it is a constant worry or issue, get some track time with a good instructor and they will work you through the art of driving a high performance car.

[Railroad]

Thanks for the reply and information. Not sure about mixing tires, now. I am running Toyo's on the rear and Goodyear's on the front of my GT500 and Toyo's on the rear and Nitto's on the front on my Mustang Cobra. I do not drive at high G's on the street, but have taken a few intro driving classes, with no bad side effects. The handling characteristics of the roadster will definitely dictate caution and adaptive learning.
With its light wt and high hp, I want to keep something sticky on all 4 corners. I am not going to say it will never be in the rain, but not intentionally, thus the desire for grooved tires.
I have not researched the Falkin's. I will give them a look.

[Avalanche325]

Mixing tires won't necessarily make the car handle poorly. It is just that it "could" and that could will show itself exactly at the worst time. So I agree that you generally shouldn't do it.

For auto-crossing, BFG Rivals are one of the hot, gotta have 'em tires. I think that would be 275 on the front, which some guys have done. The other hot autocross tire is the Bridgestone RE 71R, but they don't come in 315.

I am running Nitto NT05s on 17" wheels. They are the best street / track tire right now that you can get a few miles out of. (~10,000 miles, but I autocross) NT01s are even stickier, but you will go through them pretty fast.

[Railroad]

Thanks for the info. I think I am down to Mich Pilot 245/40ZR18 on the front,,,good tread depth, 180
AA, A BFG G-force Rivals 315/30ZR18 on the rear,,200 AA, A with a couple of center grooves.
I am still open to suggestions and advise.
Not for the track, but I do not want to say, if I had bought better tires, I might have saved it.

[Jeff Kleiner]

Please, just put Rivals all the way around.

Jeff

[Railroad]

Please, just put Rivals all the way around.

Jeff
I do not have a problem doing that. Will definitely move that to the top of the list. Thanks for the advise.

[Dthquazi]

Does the 315/30/18 fit without fender liners without any problem?

[Railroad]

Does the 315/30/18 fit without fender liners without any problem?

From reading, users have listed this size OK on the MkIV.

[edwardb]

Agree with the suggestions to stick with one brand, and highly recommend the BFGoodrich g-Force Rival S tires. On my second season in #8674 and like them a lot. These are 245/40ZR18 front and 315/30ZR18 rear. Fit fine. Some have gone to 275's in the front. I stuck with the 245's and I'm happy with them. I don't have fender liners. Assume you meant the aftermarket ones from Alex Custom Roadster? I have just the stock FF splash guards. But none of this interferes with the tires either way.

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Graduation/IMG_4515_zps23gxxyb8.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Graduation/IMG_4515_zps23gxxyb8.jpg.html)

[Railroad]

edwardb, thanks for the confirmation. I think your car sits well on the given tire sizes.

[JRL16]

My build has the same tire size that FFR suggests which is what Edwardb uses. Mine also has the fender liners from Alex's custom roadsters and there are no interference problems. I did replace 1 pushpin in each liner with an elevator bolt. It helped pull it closer to the body. The location for the bolts on the front liners are to the rear of the tires on the inside hole. This helped when the wheels were turned. On the rear liners the bolts are in front of the tires on the inside. That helped with the only close clearance issue I saw. They weren't making contact just closer than I liked. I also replaced the small L bracket for the front liners with a larger L bracket and bolted it to the 3/4 frame tube. I don't see how the bracket shipped with the liners is good long term. You definetely don't want a front fender liner coming loose at speed. Also a good idea to permanently attach the bulb seal on the bottom of the liners to keep from coming loose.

[Railroad]

JRL16 thanks for the experienced advise. I do not know whether I will be doing the liners or not, but those tips will surely reduce the chance of an issue. It took a lot of discussion, but I finally got the tire brand and size choice completed.
Thanks again,