On a 9.5 inch front rim what is the ideal tire width

6145 Views 15 Replies 8 Participants Last post by yasir, Oct 30, 2001

les

Discussion Starter · Oct 28, 2001

What are the advantages/disadvantages of going wide 275 or narrow 245-255 on the same rim. Does a wider wheel increase steering effort. How is "turn in" feel autocrossing affected.Thanks for your input guys.

1 - 16 of 16 Posts

pwpanas

· #2 · Oct 28, 2001

A wider tire on the front will increase oversteer, unless the front sway bar is stiffened (or the rear sway bar is decreased in stiffness) to compensate.

The right combo depends on the width of your rear tires, your sway bars, and the stiffness of your shocks&springs or coilovers.

Andi

· #3 · Oct 28, 2001

les said:
What are the advantages/disadvantages of going wide 275 or narrow 245-255 on the same rim. Does a wider wheel increase steering effort. How is "turn in" feel autocrossing affected.Thanks for your input guys.

Yeah, what Phil said.

...but let me elaborate... if you have 17x9.5 fronts, I'll assume you also have 17x11 rears. If you have 17x11 rears, you've already got 315's back there.....

So.. for the 17x9.5 fronts... honsetly I think the optimal size is 265/40-17. However, I consider it more important to have the SAME kind of tire rall around. Since I run BFG G-Force TA KD's (they rock; see th new issue of Sport Compact Car) and have them in 315/35-17 in back, I run these tires in 275/40-17 in front.

Andi

Hua

· #4 · Oct 28, 2001

275s up front is crazy.

I thought my 265s in the rear were big. Heh.

yasir

· #5 · Oct 28, 2001

I run 265/35 on a 18x9.5 upfront & 295/30 on a 18x10.5 on the rear with out any fender mods at all.Gotta love this set up

Regards. Yasir

Rasidel

· #6 · Oct 28, 2001

yasir said:
I run 265/35 on a 18x9.5 upfront & 295/30 on a 18x10.5 on the rear with out any fender mods at all.Gotta love this set up
Regards. Yasir

Is your car lowered? If so, what are the mods (shocks/springs/coilover?)

rasidel

yasir

· #7 · Oct 29, 2001

Eibachs with oem shocks and no rubbing or any other problem.
Regards. Yasir

G

· #8 · Oct 29, 2001

HMMM.

yasir said:
I run 265/35 on a 18x9.5 upfront & 295/30 on a 18x10.5 on the rear with out any fender mods at all.Gotta love this set up
Regards. Yasir

I've been planning on doing this setup myself, but I was playing with the ol' Texas Instrument today and noticed that a 315/30/18 (Pirelli P-zero Rosso Asimmetrico...) would seem to work if it fits ok. It would be slightly shorter than a 315/35/17 like on Andi's setup, but would be just as wide, so it *should* fit. This would provide a better contact patch if used on an 11" wheel over a 295 on a 10.5" wheel. Has anyone tried this or know if it would work ok without too much banging around under the fenders?

-R

houstonT

· #9 · Oct 29, 2001

I run 265/35/18 in front and 295/35/18 in rear. I had to cut the fenders off in the rear and take the bolts out of the fenders in the front. They don't rub at all now. The BFG G-force are a little wider that other tires in the same size though...

yasir

· #10 · Oct 29, 2001

houstonT said:
I run 265/35/18 in front and 295/35/18 in rear. I had to cut the fenders off in the rear and take the bolts out of the fenders in the front. They don't rub at all now. The BFG G-force are a little wider that other tires in the same size though...

Houston your offset is definately different than mine.I have 45mm front and 57mm rear and i didn't have to do any mods to my fenders at all.
Yasir

Steve Jarvis

· #11 · Oct 29, 2001

Of course I have the same setup as Yasir except 50mm offset front and 55mm offset rear. I also have no rubbing problem with no modifications. I have Eibach springs, KYB/AGX shocks and TRD swaybars. It's all in the offset.

You could run the 315/30R18, but you will have to roll/cut your fender lip.

Later, Steve

houstonT

· #12 · Oct 29, 2001

Yasir, as i mentioned, the BFG Gforce are WIDER than other brands in the same size. The 295's on the gforce are similar to 315's by other tire manufacturer's. I had 295/30 AVS sports and they fit with no mods, but by stepping up to the 295/35 G-force, not only is the sidewall a bit taller, but the tires are wider in the same size... I dunno why the g-force are wider... You can ask Andi, his 315's are like 335's!!!!!

yasir said:
Houston your offset is definately different than mine.I have 45mm front and 57mm rear and i didn't have to do any mods to my fenders at all.
Yasir

yasir

· #13 · Oct 30, 2001

houstonT said:
Yasir, as i mentioned, the BFG Gforce are WIDER than other brands in the same size. The 295's on the gforce are similar to 315's by other tire manufacturer's. I had 295/30 AVS sports and they fit with no mods, but by stepping up to the 295/35 G-force, not only is the sidewall a bit taller, but the tires are wider in the same size... I dunno why the g-force are wider... You can ask Andi, his 315's are like 335's!!!!!

Well Houston i'm not a tire expert but it sure doesn't make any sense

lets ask Steve Jarvis about this issue. Hey steve u listening

any feed-back. So if i need 295/30,u think i should buy 275's in G-force
Regards. Yasir

Andi

· #14 · Oct 30, 2001

In terms of section width... the g-Force TA KD is a bit wider than other tires.... but not by THAT much... maybe 5-10mm....

Andi

Steve Jarvis

· #15 · Oct 30, 2001

Luckily I have a friend that is a tire designer for Michelin/BFGoodrich so this is something I can shed some light on. The G-Force KD is about the same section width as any other similiarly sized tire. The difference is in tread width. I know someone will look at the specs on www.tirerack.com and say the tread width on the G-Force KD is less than the AVS Sport, but that is just the way it's measured. If you look at the G-Force KD you will see the tire has a very rounded shoulder. This design lays a lot of tire on the road while cornering, but doesn't give you the largest tread width while sitting still. If you lay a straight edge across the tread of the G-Force KD and measure the width about 1/4" down the side of the tire, this is where you will find the G-force KD is around 5mm wider than it's competition. This is also where our rear tires tend to hit the fender lip under typical suspension travel (higher speed cornering with street tires). You could run less than a 55mm offset on you rear wheels and never get rubbing with the 295/30 AVS Sport, but you would rub with the 295/35R18 G-Force KD. Yasir, your offset is enough that running a 295/35R18 G-Force KD wouldn't be a problem, but you wouldn't want to run a tire that tall anyways (26.1" vs. 25.0" for stock tire). You could run the 285/30R18 G-Force KD, but it would be smaller than your 295/30R18 AVS Sports. Here are the specs on some of the mentioned tires

G-Force KD
285/30R18 Section width 11.4", Tread width 9.4", and height 24.8"
295/35R18 Section width 11.9", Tread width 9.8", and height 26.1"

AVS Sport
295/30R18 Section width 12.0", Tread width 10.6", and height 25.0"
295/35R18 Section width 11.8", Tread width 10.6", and height 26.1"

A couple of notes about the above dimensions. The tread width of the G-Force is not representative of their actual width (see comments above). The AVS Sport is actually 11.8" section width and not 12.0". The above 295's were measures on 10.5" wide wheels and the 285 was measured on a 10" wide wheel. If you mounted the 285 on a 10" wheel, it's section width would probably go up about .2".

Hope this helps, Steve

See less See more

yasir

· #16 · Oct 30, 2001

Steve,i'm pretty happy with my set up and the comment about the G-force was kinda a sarcastic

thing.I knew it,that it didn't make any sense that the same size tire,could b that different in widths
Regards. Yasir

1 - 16 of 16 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.