285 rear on FD
 

Does anyone have a pic of 285/40/17 on the rear of a FD? Does it fit ok? I currently have 275/40/17 and it looks like that would be max but I would like to go a little wider if I can. Thanks!

https://www.rx7club.com/forum/attach...postid=1375082

yikes that's too tall, you'll jack up the rear end!

try 285/30-18 on 10 x 18 or 295/30-18 on 10.5 x 18 :)

Is 0.1 inch more going to jack up my rear end?
Stock sidewall 4.4 in
275/40 tire = 4.3
285/40 tire = 4.5


BTW I have the stock supension. So is anyone running 285/40/17? I need to order tires soon so please advise.

Hell go ahead and do it. Don't forget to add traction bars, Cragar 5-spokes, and red-circled bias ply tires...(jeez...if you don't get it, you don't get it...)

um...you forgot to add the 1-inch taller wheel diameter and multiply the sidewall height by 2, so I would say 1.2 inches is taller than stock....

A few knowledgeable people just did.

I remember reading an article in turbo that had rx7.com or rotary performance car with 285 rear tire, It was black with forgeline wheels. I forgot if it had 17s or 18s but 285 for sure. Not trying to be a smart ass but I just wanted to know

285/30-18 Hoosier R3S03s on 10 x 18 Forgeline RS...that was the Project Rx7 car on Sport Compact Car (over heated motor, now being done at SR Motorsports).

BTW, don't bother with Hoosiers, unless you're a road racer. Stick with road tires on the public roads.

Why are you adding 1 inch? I'm comparing 17s to 17s just 10mm wider tire with slightly larger sidewall. So I was just asking joker how he considers that "too tall" or "jacked up" The way I calculate it shows only a small difference: current rear setup is 275/40/17 (sidewall = 275 x .40 = 110mm = 4.331in) and I want to run 285/40/17 (sidewall = 285 x .40 = 114mm = 4.488in)

Cool, thats what I was trying to find the specs on that RP car. I knew those had to be 18s but for some reason they looked like 17s in the pic and had a big sidewall

You stated that the stock sidewall height was 4.4 inches. That is with a 16-inch rim. You are running 17-inch rims so you need a sidewall height of approximately 3.9 inches to maintain the stock wheel+tire diameter. You are also not accounting for the fact that you have "two" sidewalls included in the diameter of the wheel+tire.

You are right that 285/40 is not much taller than 275/40. However, 275/40 17 is already nearly an inch taller than stock. BTW, the tread width differences between a 285 and a 275 on the same width wheel will be insignificant. The only straight-line traction differences you will notice will be due to the 285/40 having a slightly taller final drive ratio, not the extra width.

...taller rear tires will DECREASE acceleration (not increase it), but will add to your top end speed (if you ever find yourself at the Indy Motor Speedway)

:doh: :stickpoke :ret::dunce: :knob: :whipit:

I honestly believe folks make WAY too much out of the tire diameters varying from stock.

THAT SAID:
you ARE pushing the envelope, and probably won't see any benefit if they're going on the same size rim. I'd stick with the 275/40's.

285/40 is a less common size and will offer fewer choices for tires. Is there some specific reason you want to do this?

Disagree. IMPROPER tire diameters can adversely affect fender clearances, acceleration potential/top speed, and ride height.

gohorns - I advise you listen to sleepR1, he is no dummy when it comes to wheels, tires and suspension...he is one of our resident experts... :)

K

Those are also adversely affected by wider tires of stock diameter, too, right? So maybe we should all stick with tires of the same diameter AND width as stock. ;)

Wade

I didn't say it didn't matter.... just that too much is made of it. Of course you can't completely disregard fender clearance and gearing... but I DO think that some folks split hairs about this a little... particulary in the rear where clearance is less crucial.

For instance, the stock diameter is 24.9".

A 275/35/18 S03 is 25.6" in diameter (this is the size i usually see people belly-ache about)

Ride height difference: .35"

So not even 3/8" of height is what everyone quibles about? Please. Unless you've corner-balanced your car with scales, you're heights are probably almost that far off from side to side by the time you sit in it.

IMO, For street i think that 275/35/18 is a better solution than the 285/30/18 with its tiny sidewalls and slightly smaller than stock diameter. My experience is, while the 30-series make the car feel more responsive, its actually a detriment to straight-line traction, and in combination with aggressive lowering make the car tough around town.

So all i was pointing out is that i believe that some sizes are a bit of an extreme to go to just to get nearer to stock diameter.

I can tell the ride height difference between my old 245/45-17--275/40-17 Hoosier setup and my current road setup 255/40-17. 0.30 inhes taller with the Hoosiers, was enough height to increase the car's roll center. This is why I'll plan 245/40-17--285/30-18 for the next setup.

Oh sure...stock tire size will stick just fine :)

Diameter does matter a lot for the front, but it is less important in the back.

It's amazing how small a difference in ride height you can notice. I lowered by car like 0.25" once and I could tell it was lower by sitting in it. I was surprised. Now, just because it is noticable doesn't mean it "matters", but I was just surprised how perceptible such changes are.

What size front tire do you have? If the rears are already a bunch larger, a 285 might be a step in the wrong direction. Not a big step, but it is still the wrong direction, so why take that step?

-Max

Absolutely... you can certainly "tell" when you've changed most anything in the suspension of these cars, and i think thats a good thing.

I was simply disputing the idea that anything larger than stock will "ruin the handling" or "jack it up", and that resorting to sizes with other shortcomings (depending on your application) wasn't always necessary.

I think most FDs (mine included) are a little over-lowered for asthetic reasons (often the rear more than the front), and i know I actually welcomed the little extra height from 245/40/17s all around to a 235/45, 275/40/17 combo. It allowed it to sit where i liked it without dragging the exhaust system off over speedbumps.

That said, i wouldn't put 285/40/17s on MY car...

...like you pointed out there aren't many tire brands that come in 285/40-17 anyway...Pirelli P-Zero Asimmetrico is all I can think of? And think how heavy a 285/40-17 tire is...gotta be around 30 lbs at least :eek:

Absolutely... you can certainly "tell" when you've changed most anything in the suspension of these cars, and i think thats a good thing.

I was simply disputing the idea that anything larger than stock will "ruin the handling" or "jack it up", and that resorting to sizes with other shortcomings (depending on your application) wasn't always necessary.

I think most FDs (mine included) are a little over-lowered for asthetic reasons (often the rear more than the front), and i know I actually welcomed the little extra height from 245/40/17s all around to a 235/45, 275/40/17 combo. It allowed it to sit where i liked it without dragging the exhaust system off over speedbumps.

That said, i wouldn't put 285/40/17s on MY car...

Plenty to choose from, you just got to look: Bridgestone RE730, Firestone SZ50, BFG Gforce, Yoko AVS Sport, Nitto NT555, Goodyear F1s, Michelin pilot a/s, Dunlop 8000s,...


Max- I have 235 on the front but if I go with the 285 out back I will get either 245 or 255 up front

"Brrrrrrrmmmm"...that's the sound of fender lips rubbing when you enter your driveway curb :)