18's or 17's, & wider tire in rear for road race?

Stangsgrl

Member
Mar 13, 2004
132
1
18
Mesa, AZ
Here's the deal. My plan is to road race more than take it to the 1/4mile. I'd like to get the most handling out of my wheel set up but not sure which is better:

1: Should I get 18's all around or I could save money and just get the rear deep dish 17's? Which would be better for handling?

2: Also, should i have an equal width tire all around or can i go wider in the rear (like 315 or 305)?

I'm looking at either ~$900 or ~$2000

thanks!
 
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Don't run a wider rear tire on a road race setup. The Mustang has a natural understeer state as it is, adding the additional grip in the rear will only worsen that condition. You can do a 9" wide rim all around and run the Nitto 285's. I think that 18's are better for handling, but some guys swear by the 17's.

It is possible to run wider rear tires but it takes substantial suspension component and geometry changes to make it worthwhile. With the stock configuration, running wider rears will make the car slower in the twisties.
 
Thanks, so well if i go with 285 all around, I'd have to get wider front tires anyway if i stayed with 17's, since i was thinking i could stay with the stock. If i do that, well i guess i might as well spend a li'l extra and get the 18's? hmmmmmmmm.......

Anyway, so does anyone else have opinions also?? :)
 
Bluepony00 said:
Don't run a wider rear tire on a road race setup. The Mustang has a natural understeer state as it is, adding the additional grip in the rear will only worsen that condition. You can do a 9" wide rim all around and run the Nitto 285's. I think that 18's are better for handling, but some guys swear by the 17's.

It is possible to run wider rear tires but it takes substantial suspension component and geometry changes to make it worthwhile. With the stock configuration, running wider rears will make the car slower in the twisties.
terrible reference. :nonono:

It is BETTER to have wider tires in the rear.
 
Stangsgrl said:
Here's the deal. My plan is to road race more than take it to the 1/4mile. I'd like to get the most handling out of my wheel set up but not sure which is better:

1: Should I get 18's all around or I could save money and just get the rear deep dish 17's? Which would be better for handling?

2: Also, should i have an equal width tire all around or can i go wider in the rear (like 315 or 305)?

I'm looking at either ~$900 or ~$2000

thanks!

1. If you get 18's all around you can maintain Stock Tire diameter by using a smaller sidewall, smaller sidewall = less wall flex in the tires. It cost more though.

2. You can run wider in the rear as long as you have enough room, usually the tail-pipes or quad shocks get in the way depending on the offset of the rim, but you can elliminate the quads by using a strong Lower Contral Arm. You can also get Wheel Spacers to open up the offset.
 
Bluepony00 said:
Don't run a wider rear tire on a road race setup. The Mustang has a natural understeer state as it is, adding the additional grip in the rear will only worsen that condition. You can do a 9" wide rim all around and run the Nitto 285's. I think that 18's are better for handling, but some guys swear by the 17's.

It is possible to run wider rear tires but it takes substantial suspension component and geometry changes to make it worthwhile. With the stock configuration, running wider rears will make the car slower in the twisties.

:bs: I'm running 285/40X18 in the back and 265/40X17 in the front and it handles much much better than when stock.
 
tomustang said:
terrible reference. :nonono:

It is BETTER to have wider tires in the rear.

Explain why please?


Road race setups are about balance. The Mustang has a balance issue in stock form simply b/c the motor is so far forward on the front wheels, giving it a natural understeer state. If you increase the rear grip (i.e. wider tires) w/o altering the balance of the car first, you have worsened the understeer condition. Which is why I said you can run wider rears, but have to modify the suspension first to make it worthwhile.
 
All SN95's have the front wheels set out father than the rear...which when using equal sized tires tend to make the rear wanna lose grip on hard cornering. So to cure that, many go with a wider rim/tire in the rear. For whatever weight it adds, it certainly makes up in handling.

By the way, go with the 18's...less sidewall to slow you down when hard cornering.
 
ShakeandBake said:
All SN95's have the front wheels set out father than the rear...which when using equal sized tires tend to make the rear wanna lose grip on hard cornering. So to cure that, many go with a wider rim/tire in the rear. For whatever weight it adds, it certainly makes up in handling.

By the way, go with the 18's...less sidewall to slow you down when hard cornering.


But that's easier cured with wheel spacers. The snap loose condition of the Mustang is not caused by balance, it's caused by rear steer due to control arm bushing sloppiness.
 
All good info...

I do plan on doing a lot of suspension as time goes on, i just need new tires right now. Guess it looks like i'll do the 18's and wider tires on the rear like i wanted anyway. Plus I guess it'd be better when i get bigger front brakes with 18's. Whew the money... :) Thanks for the replies!
 
you can set you supention up to run either way but I would want a wider tire than a 245 front and rear if I were trying to achive maximum handling. a wider rear tire can cause you to need a different size rear sway things like that if you get real technical.

I know when my car was stock the rear would slide out before the car would push through a corner so a wider tire just give you more grip.

suspention is all about balance. there is no dissadvatage to running a wider rear tier other than cost and loos of rotation ability.

my advice on suspention is listen to knowone on a message board and call a company like MM, griggs, global west. they will have people way more knowlegable than me or anyone else that will post in the thread. I love MM stuff. I would recomend anyone who wants to have a better handling stang call them. it is not the cheapest though.

as far as rim size there is also tire hieght, wheel wieght. you would need to list the rims and corresponding tire sizes to get real advice. for example if you bought a forged BBS 18 it is lighter than some 17's and if you get the right tire size you will not raise the roll center of your car. 18's would also alow you to run 14" rotors if you ever really wanted to run an expensive road racing brake system. 17's will not.
 
what's the average weight of a normal rim, and a light rim? I don't know what to compare it to with the rims i'm looking at. :)

I'll email MM and see what they say too...i don't know why i don't think about that sometimes.:nice:
 
hognutz said:
my advice on suspention is listen to knowone on a message board .

MY susp was all messed up, i listened to TOM who happend to be on a Message board who had a wide knowledge in Susp. I dont understand why people who have only seen one side of the apple cart always seem to have all the answers.


Anyway Tom told me what to do and guess what im on the way to the dyno everything is finnally working, there are people on here that know what there doing and there are people on here that dont, its your job to listen to what they have to say and pick out the guy who actually knows what he's doing..
 
Stangsgrl said:
well i don't have to run wider tires, i'm just asking which set up is better for handling? 18's or 17's? Wider tires on rear or equal size all around? :)
18's all the way around and equal size tires (275/35/18) is your best bet. Going the same size all the way around assures that you're still able to rotate the tires around for better wear and longer tread life. Pick a tire that fits as squarely on the rim as possible if handling is your main concern. A wider tire may lay down a slightly wider foot print, which is great for rear wheel traction, but a wider tire in this range is also going to have a taller sidewall, which will flex that much more under hard cornering. You may also want to look into a set of lowering springs as well, since even with the same overall diameter, an 18" wheel and tire combo is going to appear smaller than a 17" combo.