Drag Radials 18"-10.5" Question

[Pure Vennom]

What would happen if I ran 18x10.5 Drag Radials on the back and 17x9 on the front of my car at the race.

This would change my gear ratio wouldn't it?

Would this be recommended or totally wrong. Please give me some advise on this one.

 

[jmimac351]

The overall diameter of the front wheels is not relevant as it relates to rear gear ratio. In fact, the size of the rear wheel is also irrelevant. What you need to look at is the overall diameter of the Tire on the Rear. That diameter is what affects the rear gear ratio.

You have a few options:

Nitto Drag Radial in a 305/45-18. Overall Diameter = 28.78"

Nitto Drag Radial in 315/35-17. Overall Diameter = 25.79"

BFG Drag Radial in 315/35-17. Overall Diameter = 25.7"

EDITED: I just saw that BFG also makes a little different DR. The GForce T/A drag radial:

275/35-18. Overall diameter = 25.6
295/35-18. Overall diameter = 26.2

That made part of what I wrote initially, moot. With those sizes you can select the one that gets you real close to the stock tire height - if that's what you want.

Stock Tire Diameter = 25.6"

The main reason why you put drag radials on the car is to help with traction. For me, the consideration of effect on the final gear ratio would be secondary, assuming the effects are not too dramatic. In this case they aren't. The superchargers in these cars don't rely upon rpm to make boost, like centrifugal blowers. They have a broad powerband. The lower gear ratio is not going to hurt as much.

Here is what I am going to do. I am going to buy at set of 18" wheels and put street tires on them. Those will be my "pretty wheels". I am going with 18" wheels because they will look good and I can get a 295 street tire for them. Can't find a 295 for a 17" wheel. Also the wheels will weigh less than the stock 17" wheel.

For the track I am going to put on a pair of Nitto 315/35-17 Drag Radials on the stock wheels. I picked those because A) they are actually a little narrower than the BFG radials (eventhough the advertised size is the same) and they fit the stock wheel better, and B) I want to be able to run them on the street more often or drive to the track with them. The BFG tires will hook better, but they wear out much faster. With the extra meat from the nittos I am hoping I can get enough traction to make me happy. We'll see.

If you want to see the Nitto 315/35-17 tire on stock wheel do a search. Someone just recently posted pictures on those tires on the stock wheel. They fit surprisingly well.

Good luck,

Jim

 

[shetheri]

Actually, the stock tire height (overall diameter) is 25.7" not 26.7".
(((275*.4)/25.4)*2) + 17 = 25.66

The closest tire in 18" would be the 315/30 18" G-Force DR. That is what I am putting on and that is what others on here have run.

Scott

 

[jmimac351]

Originally posted by shetheri
Actually, the stock tire height (overall diameter) is 25.7" not 26.7".
(((275*.4)/25.4)*2) + 17 = 25.66

The closest tire in 18" would be the 315/30 18" G-Force DR. That is what I am putting on and that is what others on here have run.

Scott

Yep, you're right. I was looking at a chart of specs and pulled the wrong number. Thatnls for pointing this out.

Jim

 

[yelo03infl]

in a related question. i have the 10.5's in the rear i was wondering if the 295/35/18 bfgoodrich g force ta's would be wide enough or if they would be "stretching to the edge of the rim". any ideas?

 

[Pure Vennom]

So could I put a Nitto Drag Radial Size: 315/35R17 Rim: 10.5''-12'' Dia.: 25.79''? This would be no problem? This could be put on a AFS 17X10.5 wheel?

If I got a stock Wheel 17x9 would a Nitto 275/40R17 Rim: 9''-11'' Dia.: 25.63'' fit.

Am I on the right track here. Also are the BF Drag Radials or the Nitto Drag Radials better? Which one is best or are they both comparable.

 

[Pure Vennom]

__________________________________________________
Originally posted by shetheri
Actually, the stock tire height (overall diameter) is 25.7" not 26.7".
(((275*.4)/25.4)*2) + 17 = 25.66

The closest tire in 18" would be the 315/30 18" G-Force DR. That is what I am putting on and that is what others on here have run.
__________________________________________________

Scott,

Are you putting this tire on a wider wheel. The AFS that I was looking at is 10.5". the 315/30/18 I thought was for 11"-12" wheel. Is this close enough to fit?

 

[shetheri]

It will fit on the 10.5" wheel with no problems. I know that SamBandit and some others on here have run them. I still have not decided if I am going with the DR or a street tire, but I do know I am going with the 315/30 size. I have found some Michelin Pilot Sports in that size. There are not many 18" tires offered in the 315/30 size, most only go to the 295/35. I want as much tire as I can fit on the rim, though. Check out the below thread.

http://www.svtperformance.com/forums/showthread.php?s=&threadid=38223&highlight=drag+radials


Scott