sxviper

I have talked to 3 different tire/wheel vendors about tire/wheel setup and I can't seem to get a consistant answer on what is right and what is wrong and the reasoning behind it. This is my question...I want to put 20x9 rims in the front and 20x10 rims in the back. I have been suggested to put 245/35/20 in the front and 275/35/20 in the back but the tires I want are the Toyo T1S and they don't offer that. The next vendor said it is ok and they put 245/35/20 in the front and 275/30/20 in the rear all the time without any problems. The first vendor said it will not work and I will have traction control problems. Can anyone give me the math and reasoning behind why this will and will not work? I keep hearing you need to keep the ratio from stock to new in the 1 to 3% range....what ratio are they talking about? Overall diameter from the front stock tire to the new front tire? Please help!! I ended up just ordering the 245/35/20 and 275/30/20 setup so I hope I didn't make the wrong choice.

d21arren

iTrader: (1)

yes you ordered the correct size. what they are talking about is the overall rear tire diameter has to stay the same or it will mess with your traction control. Im in the same place you are trying to find tires to fit a 20" rim is hard to do. so what rims and tires did you order?

FB-350

i've got the sizes you ordered...

sometimes on a highway on-ramp or off ramp, if my TCS is ON, i occasionally get the SLIP SLIP SLIP light flashing, and the ECU slows down the car for like 2 seconds... nothing major..

i'm in the habit now of just turning off the TCS when i get in...

i only use the TCS in the rain now....

Todd@ProDyno

fb...can you see the height difference. Id hate having a shorter rear tire, which is the issue here.

sxviper

I am glad to see the replies. I decided to go with the Axis Se7en Mods and then have them chromed. I chose the Toyo T1S in the 245/35/20 and 275/30/20 setup. I will post pics once I mount them.

As far as a height difference the front (if my calculations are right) will be 26.8" and the rear 26.5" so we are talking less than a 5/16" which I can't imagine is very noticealbe at all....but I will see soon enough. And the front side wall will be 3.4" and the rear 3.2" which is less than a 1/4" so I think it should look just fine.

Thanks for the replies.

FB-350

height wise - they look about the same due to the 275 rear...
i know of a few other members who've had similar incidents with the SLIP coming on...
if i went with a 285 or 295, i think i may have no issue at all...

jckolnturn

iTrader: (1)

You are still going to have VDC problems because the rear is smaller than the front so it's going to spin faster than the front tricking the car into thinking it is slipping. Did you consider 19's for the front with 20's in the rear?

Fb you will probably be fine with the 295's but will the fit without rolling or is that already in your plans?

xsmallpaulx

iTrader: (3)

you got the correct size man

FB-350

Fb you will probably be fine with the 295's but will the fit without rolling or is that already in your plans? [/B][/QUOTE]

I will probably go ahead and have the fenders rolled just as a precaution... a few of the local wheel shops have a machine that does it for $40 i think... i just got the wheel/tire setup in december, so (hopefully) i've got a little more life left on what i've got...

jckolnturn

iTrader: (1)

post pics when you're done

Sharif@Forged

iTrader: (92)

Aaaaaaaaahhhhhh...the madness continues!!

The 30 series tire will NOT be taller than the front 35 series. Aspect ratios are...just that...a ratio between width and height. Since the back tires is wider, you need a smaller aspect ratio to compensate. If anyone still has doubts...I can post pics of my mis-matched (I believed the idiot at the tireshop) tire setup. I went with 35 series front and back and the back is DEFINATELY taller than the front. Oh crap...wait...my car is in the shop for a while. OK..well just believe me then!

Dude...you got the right sizes!! )

jckolnturn

iTrader: (1)

my bad

NOZ4U

I went with seven mod's as well in 20's. I got 275/30/20.9 in the front and 285/30/20.10 in the rear. Wheelstudio.com said that the 275/30 in the front was the closest to the stock setup and he guranteed that this is the best tire size. However, I don't have them as of yet so I don't know. If that doesn't work out, I know a guy who's running 255/30 in the front without any problems. I'll post pics as soon as they go on Thursday.

sxviper

I went with Wheels Studio as well. My setup should ship this week. I will post pics when I get them installed. They recommend me to go with the 245/35 and 275/30 setup.

NOZ4U

That's funny that they recommened that size cause Gabrielle insisted that the 275 in the front was the correct size. Kinda makes me wonder though. You're lucky. I bought these back at the beginning of Feb and I'm supposed to get them Thursday. The 275/30 better be correct because I'm tired of dealing with wheelstudio.

sxviper

I just talked to Gabrielle and I changed my order to the Bridgestone tires with the 275/30 front and the 285/30 rear. Where you waiting on the wheels or tires? My wheels I had chromed so that is why I am waiting. He said he would have my tires in stock in a few days. For what its worth...those guys have been very helpful. I just hope I don't have wait forever to get them.

NOZ4U

The 275/30 in the front fits perfect. No loss in turning radius or rubbing. There's no loss in responsiveness either. The 275 in the front fills out the wheelwell perfect. With the 275/30/20FR and 285/30/20RR, it makes the car .6in taller. However by looking at the car from the outside, it looks lowered. I assume this is because the fender gaps are all but gone as they are when a car is traditionally lowered. I plan on having the Tein S-Techs put on this week which should lower the car back to stock height but appearance-wise, it's gonna look slammed. Trust me when I say, you got the right set up. I was actually surprised (being that the sidewall is so small) the ride comfort is much smoother with the wider tires in the front and back. I assume because it's such a larger contact path, it can absorb more vibrations.......who knows. The car feels as if it's planted firmly on the road.

joust75

iTrader: (1)

You should have kept the aspect ratio the same.
The rear tires need to be taller than the fronts. With your setup the overall diameter is going to be almost the same.
I run 255/35 front and 275/35 rear and I have no problems whatsoever
In contrast when I first changed out rear tires on my track wheels I went from 245/45 to 255/45 without changing the 225/45 fronts. My VDC cut in some times on curves. Dangerous! So with the track wheels I went 235/40 front and 255/40 rears. problem solved

A good way to figure out what tire sizes are right for you is to increase front and rear tire sizes proportionall to eachother.

For instance when I upgraded to TE37s I wanted 275/35 rears. That is up 30 and down ten on the aspect ratio from the 245/45 stock rears.

To determine the size to get for the fronts all I did was go up 30 and down ten on the stock front size of 225/45.

Presto, perfectly proportioned 255/35 fronts 275/35 rears.
I have had o problems with VDC and I have tremendous grip.

SX Viper, you are going to have issues with TC and VDC if youve got it. I advise you not to put the tires on that you ordered and order tires that are proportionally staggered.

sxviper

I am all over the map with this issue. I have talked too about 3 tire/wheel vendors and they said my setup is right. I am not saying your wrong at all. I will just have to see when I get them. I never drive with the TC/VDC on so maybe it won't matter. I only drive this car 4 months out of the year and it is just summer/dry driving.

NOZ4U

[QUOTE]Originally posted by joust75
[B]You should have kept the aspect ratio the same.
The rear tires need to be taller than the fronts.


Wouldn't the rears be taller in the rear as long as it's a wider tire?
If the tire size was the same front/back, the car would be the same height considering they both had the same aspect ratio. My front stock wheels (225/50/17) had an overall height of 25.9in. The rears (235/50/17) were 26.3in. This was the factory stock setup, nothing changed...nothing added. When I went with the new set up, the fronts (275/30/20) now have a height of 26.5. Half an inch or 2.5% difference. Well within the reccomended 3%. The rears (285/30/20) now have a height of 26.7in. That's .4in or 1.8% difference, again well within the reccommended 3%.

On the flip side, if I ran the same size wheels(20in) with the 245/35-275/35, the fronts would go from a stock height of 25.9in to 26.8. That's a difference of 1.1in or 3.5% in the front and the rears would go from 26.3in to 27.6in. That's a difference of 1.3in or 5.1% .