New Tires on 18" rims, what can I do ?

flo · 03-23-2009

I would like to go on smaller wheels (smaller diameter).
The gear ratio 3.55:1 and the suspension height are stock but I would like to have better handling.
The OE are 235/50R18 on fan blades wheels.
I would like to know what tire size is OK on 18" wheels ?
235/45
245/40
or others
What are the different choices for wheels ?
Thank you

flo · 03-23-2009

I would like to know if it's a good idea to go on smaller diameter wheels.
The gear ratio 3.55:1 and the suspension height are stock but I would like to have better handling.
The OE are 235/50R18 on fan blades wheels 18x8.5.
I would like to know what is the best tire size ?

What about handling when you have a different size at the front and rear ?

Back@itagain · 03-23-2009

The diameter of the wheel you select should depend on what you want from your ride. The 15 inch wheels are great for strip action since it has a taller side wall which is more flexible and will increase traction. An 18 inch tire still provides a good side wall for traction and will absorb bumps in the road well. It will also permit the use of larger brake combinations. 20 inch diameter look great but the increased weight will have an adverse affect on horsepower, handleing and life expectation of many of your suspension parts.

The width of the wheel is what will determine the size of the traction portion of the tire you can mount and is not determined by the diameter. A lot of S197 owners are running 9 inch in the front and 10s in the rear allowing for 255 and 275-295. Some guys have squeezed 10 1/2 inch wheels under the wheel wells. All depends on the back spacing. Hope this helps.

Stoenr · 03-24-2009

255/45/18 will be your best choice for that wheel when it comes to handling.

flo · 03-24-2009

Thanak you.
Well I don't want to loose traction so does the 245/45R18 will be too small ?
The best size for 18x8.5 is 235-245 width and the max is 255.
Are you sure the 255/45r18 will be OK on the track ?

Stoenr · 03-25-2009

Perfect on the track. Ran them plenty, in the dry and a downpour.

flo · 03-25-2009

Great picture.
Did you have the fan blade wheels ?
Do you think that 235/50R18 front and 255/50R18 rear will be good or is it better to have 255/50R18 front and rear ?
I don't want to loose agility and promptness on slippy road.
What do you think ?
The Good Year eagle F1 assymetric are available in both size.

Stoenr · 03-25-2009

Personally I would keep them all the same size on those wheels.
255/45/18. Get the F1 Supercars, not assymetrics as they are the same tread pattern, and ALOT cheaper.

I ran the F1 GS D3's on my fanblades 255/45/18

Now I have wider rear wheels and run 285/40/18 rear 255/45/18 front because I wanted the staggered look, and better street hook up. It wasn't the best choice for road racing, but still very doable.

flo · 03-26-2009

I look at pictures on the forum and I'm scared of the 255/45R18 at the front they are very close of the fender.

So first I will change the rear tires for 255/45R18 but I will keep the BFG KDW 235/50R18 because they're worn at 50% and I will test
that on track.

is it safe or is it idiot ?

After I will install fours 255/45R18.
The eagle F1 supercar are not available in France.

Back@itagain · 03-26-2009

actually less tread on the tire is favorable. Most race teams shave their tires for increased performance. I think MM&FF even did an article on this recently.

255's will fit under our fenders. Some guys even have up to 275's but again it all depends on the offset of the wheel. Positive offset can be increased on your factory wheels by shaving the back pad. Just becareful and remember that you are reducing that amount of material and potentially lowering the streeng of the lug bowls.

Stoenr · 03-26-2009

Quote:

Originally Posted by flo

I look at pictures on the forum and I'm scared of the 255/45R18 at the front they are very close of the fender.

So first I will change the rear tires for 255/45R18 but I will keep the BFG KDW 235/50R18 because they're worn at 50% and I will test
that on track.

is it safe or is it idiot ?

After I will install fours 255/45R18.
The eagle F1 supercar are not available in France.

You will not be close to hitting the fender at all with 255/45 on the front. Stock or lowered it is not an issue.
Not sure I would feel comfortable with that setup on a track. Although it may help with under steer, but I'm not one to really answer that.

France, gotcha.

Quote:

Originally Posted by Back@itagain

actually less tread on the tire is favorable. Most race teams shave their tires for increased performance. I think MM&FF even did an article on this recently.

255's will fit under our fenders. Some guys even have up to 275's but again it all depends on the offset of the wheel. Positive offset can be increased on your factory wheels by shaving the back pad. Just becareful and remember that you are reducing that amount of material and potentially lowering the streeng of the lug bowls.

Shaving the tire does give it less flex in the treads, giving you quicker response. I'd rather wear them down the old fashion way, lol. Too expensive just to go and shave them, for me at least. And I work for a major tire company and get them on the cheap.
I would never alter a wheel in that way personally.

flo · 03-26-2009

Would you feel confortable with 4 good year tires 235/55r18 at the front and 255/45R18 at the rear ?
I think this the last question ! lol
Thank you guys for your help.

Stoenr · 03-26-2009

Honestly, no.
Ask as many questions as you want, thats why were all here!
Maybe post it up in the road racing section as well
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