18" vs 20" wheel performance

[66shortwide]

Guys,
I thought this was asked before, but couldnt find anything on it. If going for a autox and road course package - is there an advantage of using one or the other? All things being considered even - tire height and width - what should i go for? I know I see alot of the competition camaros and corvettes running 18's, but I figured that was due to spec tire rules.
Dont want to start the whole 18's will ride better, 20's look too big kind of debate - this is strictly performance related to the racetrack.

[SCOTI]

Originally Posted by 66shortwide

Guys,
I thought this was asked before, but couldnt find anything on it. If going for a autox and road course package - is there an advantage of using one or the other? All things being considered even - tire height and width - what should i go for? I know I see alot of the competition camaros and corvettes running 18's, but I figured that was due to spec tire rules.
Dont want to start the whole 18's will ride better, 20's look too big kind of debate - this is strictly performance related to the racetrack.

Bigger diameter wheel = more mass to get moving or to stop.
The smallest diameter that will allow the biggest brakes you intend to utilize will do the best typically w/auto-x.

[andrewmp6]

I'm with scoti and i will add you can get light weight rims 18s and 20s but the 18s are cheaper,And on tires im sure the 18s are probably cheaper then a 20.

[Ziegelsteinfaust]

There is also rotational mass. The further out the mass is the harder it is to slow down. That plays into the rim vs brakes.

People also buy rims based on looks, and not performance. So they may like 20's more then 18's. Or the other way too.

Also the ride when handling, and some people set a car up to their taste. Not necessarily what handle's best. That way they could drive it around for fun without having to swap tires.

If I was going to slam my C20, and use it to terrorize the corners. I would likely use steel 17's from Summit. I can get performance 17's cheap, with ride characteristics I like, and they were built for suv's weighing 1500 pounds more then my truck. So I could still use my truck for a bit of actual work, and not exceed or get close to the tires limits.

[N2TRUX]

If your truly building your truck for performance purposes, you need to consider what tire your going to run first. Does the size and rating you want come in an 20 or is it only available in an 18. Normally I would say go with 20 because tires in the size you need are mass produce making them cheaper than 18's. In the case of true performance tires I feel there are probably more 18s that 20's.

[knomadd]

Camaros and Corvette's run 18's because they fit better and leave some cushion to protect the rim from digging into the pavement when cornering. They may be able to stuff a 20 in there but not with much sidewall. On the older trucks, there's more room for bigger wheels with similar sidewall proportions. an 18 on a Camaro might have the same sidewall proportion as a 20 on your truck. There is a point when more sidewall is a bad thing. It will allow the sidewall to roll under the wheel in a hard corner, which is why nobody really likes using 15's when running a road course or autocross.

[Hertzdaddy]

If you want a performance tire that's wider than 275 then you need 18's rather than 17's. I'm having a hard time finding a wide 17.
Posted via Mobile Device

[07XCSBZ71]

Originally Posted by Hertzdaddy

If you want a performance tire that's wider than 275 then you need 18's rather than 17's. I'm having a hard time finding a wide 17.
Posted via Mobile Device

You're not looking in the right places. They're ton of wide 17s.I'm running 285's on a set of wheels on my Vette,a set of 315 street tires on another set wheels and NT01 Nittos on my track wheels for my Vette.

OP, another thing you have to remember is your budget. I've seen the 19" knock off Vette wheels crack and break under extreme cornering with super stickies, like my NT01,R888,R6 etc. When you throw one of these trucks into a hard turn, there is a lot of force on the lug nut area. If you have the money for a good 20" wheel and a good tire and this is going to be you only set of rolling stock, get what tickles your fancy. IMHO, I would go 18"s for cost and easy of tire location. You might be at an event, have a flat, and be able to borrow or buy a used tire from another competitor. I rarely see 20"s of a real purpose built rig around here, not says 20's are not used, just I don't see them. Most people around here run 17's and 18's.

[66shortwide]

Thanks for the info guys. The original plan was to run 275/40/20 and 315/35/20 nitto invo's on the truck - but i've found some 18' wheels i really like and debating on just running the new goodrich rival 295/35/18 on all four corners.

[Hertzdaddy]

Originally Posted by 07XCSBZ71

You're not looking in the right places. They're ton of wide 17s.I'm running 285's on a set of wheels on my Vette,a set of 315 street tires on another set wheels and NT01 Nittos on my track wheels for my Vette.

Where did you find the street tires and what brands? Also, I should have said I'm having a hard time finding wide 17's with the aspect ratio I'm looking for. I'm trying to get around 29-30" tall.

[ulakovic22]

There is always a trade off. Invo's are good tires, sticky but you can actually get some mileage out of them.

[68Stepbed]

Originally Posted by Hertzdaddy

Where did you find the street tires and what brands? Also, I should have said I'm having a hard time finding wide 17's with the aspect ratio I'm looking for. I'm trying to get around 29-30" tall.

They're not available. I've searched everywhere. There are sticky 17" tires but they're what I call "car sizes"(low sidewall). When looking for "truck sized"(tall sidewall) 17" tires, there's very little available, and literally no sticky versions available.

I'll be switching to 18's soon and running a 285/40/18 front and 295/45/18 rear. Both of these sizes are available in mild and sticky versions from different manfacturers, but I'll run the Nitto NT555, and if I'm feeling froggy(and have the extra money) these are available in the Nitto NT01.

[wraprail]

Check a place like TireRack for sizes in R compound tires.
Hankook Z214 they have mucho 18" zero 20"
BFG R1 has a half dozon 18", zero 20"
Toyo R888 they have lots of 18" sizes and only two 20"

There just is not a lot of 20" R spec tires out there. That is why you see so few.

If you are serious don't waste your time with street tires. You will chew them up and they won't be worth a crap on the road anyway. Plus they don't stick worth a ****. I have used both street Hankook V12 and Nito NT-01s and its like night and day. If you aren't serious and don't mind being in everyone elses way, use street tires.

[66shortwide]

with alot of the autox stuff going to 200 treadwear are higher it limits the use of "race" tires. I know scca stuff is different, but must of the goodguys and shootout stuff require 200 treadwear.

[wraprail]

In that case I would use Hankook RS3s. They have a 140 treadware rating but have raised it to 200 now. From what I have read the tire compound is the same. They are a street tire but really a race tire. I never ran them but some guys did in the series I competed in.

I just checked TireRack and they have RS3s in fourteen sizes 18" and only two in 20"