How wide tires for 650 hp?

[erlendch]

A shop is building a pro-touring Charger for me. It has a modern Hemi with 650 hp. We are going with 20s, and we are making the wheel wells a lot bigger to accommodate. I was hoping to get advice on how wide they should be? How wide is needed with that amount of power?

[myk]

I would think you'd have to test and tune different widths of tires to get the optimum results, or see what you like.  Different widths would alter how the car handles and your preference for the way the car handles is subjective.  Maybe someone in here running 20's could offer advice?  Board member and road course racing driver MSRacing89 runs a 19" tire out back and with a 295 wide tire for his '68, so for you I'd start there...

[Mike DC]

              
The low & midrange torque makes you need rubber more than the HP figure.

On a car the size & weight of a Charger it's pretty hard to overdo the tires.  You will probably run out of room under the chassis (or decide it looks goofy, or find something you don't want to cut, etc) before you run out of benefit from going bigger.

 

I recall Mark Stielow talking about one of his '69 Camaro builds a few years ago (the Mule?).  He picked out the biggest mass-production OEM street tire he could find (for hi-po sports car purposes).  At that time that was the rear tires off a Dodge Viper.  He started with that tire and built the rear of his Camaro around it.  
               

[cbrestorations]

i know guys running 1500hp on 9" tires. on a 20" rim ur screwed, there will be no traction compared to a 15". there is no sidewall on a 20" rim and thats where you get ur launch from. you would have more grip on a 15x8 rim with a drag radial than you will with a 20x11 rim with a drag radial aswell. if you look at the tire patch on the ground and did a square inch comparison the larger rim cars loose. you also have to run much more air pressure to hold the car up with thin sidewalls reducing ur grip even more.

[myk]

But would that apply to his "pro-touring" goals?  I don't think straight line domination is his intention.  Then again, even for a road course car I wouldn't go larger than 19".  Hell I won't do anything bigger than 18" on mine...

[cbrestorations]

even formula 1, the fastest road racing cars in the world have good size sidewalls to them

[myk]

Like how much?  Personally, I would feel the 20" wheel would add too much rotational mass and inertia, hurting performance; that would be my concern...

[JR]

I'd just go for a 20x10 wheel and be done with it. You can fit a 10 inch wide wheel in the rear of a 2nd gen without cutting anything.

That should be enough if you drive it sensibly. Thats more rubber than the hellcats get from the factory.

[XH29N0G]

I know nothing about 20 inch rims and my car is not in that range HP wise, but is close to 600 ft lb.  For me, an important consideration was the tire rubber compound. 275 x 15 wouldn't hold in second below 35 mph and all of first was useless.  255 x 15 with a softer compound will hold from a stop without dropping the clutch from high RPM.   

[alfaitalia]

Too much tyre and too much grip ruin a powerful rear drive car to me. You need just enough to keep it safe for normal driving but not so much that your cant steer from the rear on a moderate amount of throttle. If you need a great boot full of throttle to get the rear moving it will lack on the limit feel and adjustability ....and will be gripping one second then in a ferocious slide, that you probably wont catch, the next....its all about grip to slide transition.

Also great wide tyres will give you less grip in the rain due to less lbs per square inch of contact patch to push the tyre down through the standing water. Hello aquaplane....hello lamp post! LOL! If you never use it in the rain then don't worry about it!

[Mytur Binsdirti]

7.75 X 14 should be fine.

[Mike DC]

7.75 X 14 should be fine.

I guess the whole thing depends on what your idea of "good" traction is.  Fun to drive?  Safe to drive?  Hardest G-force, period?  Straight line vs cornering? 

[erlendch]

I dont care how fast it goes in a straight line, but not just spin, need to be able to handle the power and it should do corners well. My shop recommended 20 inch 345/30/20 in the back and 275/35/19 in the front, but I was getting concerned as 345 looks like a monster tire to me and I'm afraid it be tacky.. Trying to keep things subtle..

[comet_666]

Personally a 20" wheel is not particularly subtile. Not saying it looks bad but it is noticable for sure.

[Lennard]

  20" and not tacky don't go together.

[erlendch]

Have you seen the Detroit Speed Mayhem build? Just Google it, plenty of pictures. Now I would pick a less screaming color, keep bumpers in chrome, definitely don't use modern rear lights and there are many more things I don't like on the car, but it has 20 inch wheels and with that stance I'm surprised that I don't find them too big, just scare wide..

[Lennard]

I just checked them out. They would look great on stage coach.

[erlendch]

How do you like this wheel?

[keepat]

Looks great! It has a magnum 500 look to it!
Pat

[phantom]

I just checked them out. They would look great on stage coach.

Not everyone is into 14" dog dishes or 15" Magnums.

BTW, awesome wheels, erlendch  

[68pplcharger]

How do you like this wheel?

wheel looks sweet...

I've got 17x11" on the rear of mine and it looks great. Doesn't
give the car that cartoon look like a 20" does... IMHO   I've got 17x9.5" rims on the front. My car is set up to handle the corners and does that awesome. I don't have track testing yet, but the feel of the car in the corners is amazing. I haven't even tuned the suspension on the charger yet and it blows away my BWM 135i with the factory M handling package. Mine has a lot more than 650hp and the GSD3 compound tires (same as racing tires) works very well. The car pulls like a rocket is strapped to your ass.

[out there]

That is a great looking rim. Looked up the Detroit Speed build.   Sweet!

[WHITE AND RED 69]

Pick a tire that is the same size on a car from the factory. That way you know that a tire manufacturer will always make that size and not become discontinued. Nothing worse than not being able to find a replacement tire when you need it. If you are dead set on that big of a tire on the back go with a 345/35/19 same as a 2006-09 viper.

A 345/20 is going to leave you a slim tire selection. Also a 30 series tire is going to be rough on the streets. You are going to feel every bump, crack, and pothole out there no matter how good your suspension is. I wouldn't go with anything lower than a 35 series for something used on the street. 

What suspension setup are you going with?

[Lennard]

I just checked them out. They would look great on stage coach.

Not everyone is into 14" dog dishes or 15" Magnums.

BTW, awesome wheels, erlendch  

The wheels look great.  It's the rubber band tires around it that makes it look  .

[JR]

That is a great looking wheel. Go for it, dude.