Questions about tires...

Her99GT · 06-14-2001, 11:02 AM

I have a '99 GT that I just bought tires for, they are 255/40/17 all the way around. My husbands question is are these tires going to hurt the car because Ford's specs say that the car should have 245/45/17. I told him that it is not going to hurt the car just because they are wider. He is concerned because I told him that when I drive the car it seems that you have to steer more, but I think it is because the tires are wider. Also, why do some people put smaller tires on the front and wider tires on the back? One more question, does the 255 number tell how wide the tire is and the 40 tell how tall the tire is or do I have it reversed? Thanks for you patience.

Dark Knight · 06-14-2001, 11:21 AM

shouldnt hurt it at all..
255 is the width, the 40 is the height..255mm wide and 40% of the width is the height...people put narrower tires on the front and wide on the rear for less rolling resistance on the front and better traction on the rear,,, for drag racing anyway... sometimes the front tire size is limited by the stearing...the tire will rub if it's to wide... ;-)

------------------
84 convt,'95 302,AFR's, performer
3.55's, underdrives stock shorties
stock cam, 1.7's
14.06@100.21, 255RWHP on a hot day
265 on the mph/weight chart

fordgasm · 06-14-2001, 12:44 PM

Tell your husband not to worry...you got things under control. Changing to the wider tire not only looks better but the car will handle better. It may feel like it gets caught in the road, like your in ruts or something. That's the nature of the beast, the wider tires will feel that way on some roads under certain conditions.

Most mods go that way, you have to give something up to gain something else. In my opionion, the wider tires look better and handle better, so the little you give up in this case is worth it.

Now you need the lowering springs for even better looks and handling. The car will feel like it is on rails when you hit the corners with your GT...bounce that one off your hubby and see if he raises is eyebrow with concern...

------------------
fordgasm
CLICK HERE to see my 87 GT

blue00gt · 06-14-2001, 04:03 PM

The tires you got are slightly shorter than the stock ones (245x.45=110.25mm>255x.40=102.0mm) so your speedo will read high by about 1 mph at freeway speeds due to the difference(not a big deal considering the stock speedo is already off by more than this from the factory). Mine steers a little heavier with 255x40/17's in the front also.

[This message has been edited by blue00gt (edited 06-14-2001).]

mark sweetser · 04-12-2005, 11:55 PM

I've got 275/40-17's on all 4 corners... the front passenger side tire rubs slightly on the sway bar at full lock. The car tends to wander in ruts in the road, and their worse in the rain (wider tires decrease the overall weight over any given square inch of the contact patch, which hurts wet traction, but aids in dry traction). My car seems more "sure of itself" when cornering. From behind the car looks tough, especially w/ my Eibach 1.5" lowering springs installed. Heard the biggest that will fit out back is 315's (mm wide), which would look sick, but I like to have the option of rotating tires from front to rear (directional tires) w/ no problems...so I'll stick to the 275's. The speedo difference isn't even noticeable. Dark Knight is right concerning tire sizing. Try to convince hubby that the dry traction and tough stance far outways the crappy wet traction. Hope to help!

Crazy Horse GT · 04-13-2005, 01:20 PM

i have the stock 245's on front & 315 35's on the rear, i love it, still drives great & look's really good, just cant rotate, but who cares.

mustangII460 · 04-13-2005, 04:01 PM

June 14 2001?

I thought I was bored.

06-14-2001, 11:02 AM	#1
Her99GT Registered Member Join Date: Apr 2001 Location: Houston, Texas USA Posts: 11	Questions about tires... I have a '99 GT that I just bought tires for, they are 255/40/17 all the way around. My husbands question is are these tires going to hurt the car because Ford's specs say that the car should have 245/45/17. I told him that it is not going to hurt the car just because they are wider. He is concerned because I told him that when I drive the car it seems that you have to steer more, but I think it is because the tires are wider. Also, why do some people put smaller tires on the front and wider tires on the back? One more question, does the 255 number tell how wide the tire is and the 40 tell how tall the tire is or do I have it reversed? Thanks for you patience.

04-12-2005, 11:55 PM	#5
mark sweetser 96GREENGT Join Date: Mar 2005 Location: las vegas Posts: 51	Re: Questions about tires... I've got 275/40-17's on all 4 corners... the front passenger side tire rubs slightly on the sway bar at full lock. The car tends to wander in ruts in the road, and their worse in the rain (wider tires decrease the overall weight over any given square inch of the contact patch, which hurts wet traction, but aids in dry traction). My car seems more "sure of itself" when cornering. From behind the car looks tough, especially w/ my Eibach 1.5" lowering springs installed. Heard the biggest that will fit out back is 315's (mm wide), which would look sick, but I like to have the option of rotating tires from front to rear (directional tires) w/ no problems...so I'll stick to the 275's. The speedo difference isn't even noticeable. Dark Knight is right concerning tire sizing. Try to convince hubby that the dry traction and tough stance far outways the crappy wet traction. Hope to help! __________________ -'96 GTS Deep Forest Green Metallic- 8#Powerdyne,Bassani Cat-X,2 chamber Flows, FMS alum. DS,Kenne Brown subframes,Pro 5.0 short throw,FRPP 3.73's,Accufab Plenum/75mm TB,11# blower pulley,Bassani mid headers,Eibach 1.5" springs,17" Cobra R's w/ 275/40zr-17 g-force kd's,Centerforce Dual Friction -'87 Black LX 5.0 BBK shorties&Cat-X,2 chamber Flows,MSD ign,stock 3.08's,MGW short-throw,BBK cold-air,King Cobra clutch,235/55-17(F)&255/50-17(R) Kumho Ecsta's on 95 Cobra R 4-lugs

04-13-2005, 01:20 PM	#6
Crazy Horse GT Registered Member Join Date: Aug 2001 Location: Sale Creek, TN. C. S. A. Posts: 4,652	Re: Questions about tires... i have the stock 245's on front & 315 35's on the rear, i love it, still drives great & look's really good, just cant rotate, but who cares. __________________ 95 gt vert, lot's of stuff, it aint slow. 04 sonic blue v - six my beater 89 rs camaro iroc turbo hood, other stuff, my wifes ride 84 lx stang cammed up 289 hi po, etc 65 falcon, maybe by the year 2020. black 00gt, gone but never forgotten. R H C- member # 1 o.b.c. da prez- member # 1 if your under 40 dont ask. goodbye for now odie,r.i.p. 11-27-03

04-13-2005, 04:01 PM	#7
mustangII460 Factoy Five Roadster Join Date: May 2000 Location: Sevier Co,Tennessee Posts: 1,681	Re: Questions about tires... June 14 2001? I thought I was bored. __________________ Frank

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06-14-2001, 11:21 AM	#2
Dark Knight Registered Member Join Date: Oct 1998 Location: Az Posts: 854	shouldnt hurt it at all.. 255 is the width, the 40 is the height..255mm wide and 40% of the width is the height...people put narrower tires on the front and wide on the rear for less rolling resistance on the front and better traction on the rear,,, for drag racing anyway... sometimes the front tire size is limited by the stearing...the tire will rub if it's to wide... ;-) ------------------ 84 convt,'95 302,AFR's, performer 3.55's, underdrives stock shorties stock cam, 1.7's 14.06@100.21, 255RWHP on a hot day 265 on the mph/weight chart

06-14-2001, 12:44 PM	#3
fordgasm Registered Member Join Date: Jan 1999 Location: Clayton, North Carolina, USA Posts: 803	Tell your husband not to worry...you got things under control. Changing to the wider tire not only looks better but the car will handle better. It may feel like it gets caught in the road, like your in ruts or something. That's the nature of the beast, the wider tires will feel that way on some roads under certain conditions. Most mods go that way, you have to give something up to gain something else. In my opionion, the wider tires look better and handle better, so the little you give up in this case is worth it. Now you need the lowering springs for even better looks and handling. The car will feel like it is on rails when you hit the corners with your GT...bounce that one off your hubby and see if he raises is eyebrow with concern... ------------------ fordgasm CLICK HERE to see my 87 GT

06-14-2001, 04:03 PM	#4
blue00gt Mustang Addict Join Date: Jan 2001 Location: McKinney, TX Posts: 1,294	The tires you got are slightly shorter than the stock ones (245x.45=110.25mm>255x.40=102.0mm) so your speedo will read high by about 1 mph at freeway speeds due to the difference(not a big deal considering the stock speedo is already off by more than this from the factory). Mine steers a little heavier with 255x40/17's in the front also. [This message has been edited by blue00gt (edited 06-14-2001).]