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 :)

I also didnt listen and put some wide rubber on my FD and am paying for it. The fronts dont like a much wider tire but the rears can handle a pretty wide tire as long as a few things are considered. First of all the size tires and wheels I run are 255/35/18 up front on a +40 wheel offset. Stock type struts and HKS lowering springs. I had first went with H&R springs but it was just too low up front. Pulled my fender lips down, broke the paint and rubbed in the fender well also. It didnt rub unless I was turning hard into a driveway or onto a road but when it rubbed it cut up the tire and trashed my fender lips. Even rolling the fenders will only help say 80% of the rubbing. I changed the springs out to the HKS springs but it still rubs a little. I think I am doomed unless I change the tire size or change the struts to coilovers so I can run more offset and stick the wheel inside the wheel well further. That means selling the front wheels and buying something like a +42 or +45 etc. You cant really do that with stock springs and struts because the diamter of the spring is too big and the tire will touch the spring. Coilovers use a smaller spring diameter and will accomidate more wheel inboard towards the struts and springs. This is the route I will be going I think. The REARS fit great with 285/30/18's also with a +40 wheel offset. I think it makes a significant difference that they are 18 and not 17 inch wheels. The extra inch of wheel diameter does help it clear the trailing arm because of the angle the trailing arms sits. I would not try it with a 17 inch wheel with stock trailing arms. The M2 trailing arms will free up enough room because they are thinner than stock and probably accomidate the 285 17's. Ride height is also a consideration but even with lowering springs I have used and the offset of the wheels the rears are fit fine with no problems and no rubbing what so ever. By the way the wheels and Volk TE-37's 18x8.5 in front and 18x9.5 in rear with bridgestone S-03's 255/35/18F and 285/30/18R. good luck.

I got boned this way as well. Tire rack sold me 17x8" +38 SSRs for the front, and i don't think thats enough offset. The rears are 17x9 +45, and i would have used a 17x8 +45 front if I had it to do over again.

FWIW, I've been running 255/40-17 all around, on 9 x 17, 45-mm offset SSR Integral A2s with H&R springs. Over a year and no rubbing problems.

zoomzoom - I will check to see how much clearance I have on my trailing arms next time I have my car on a lift. Do you have a pic of the 285 rear? thanks!

I do but I am in NJ at work and wont be home for a couple weeks. My car is at KDR in PA and will get it back soon I hope. I can snap some pics to show you if I pick it up this week. Just remind me in a week or 2. I had some on the forum but they have since dissapeared. Guess the host deleted them. They were in the Wheel/tire section on the sticky.

I have 285-30-18 with 18x10 +49 on the rear of my fd with no fitmet or rub problems (they come close to the link and the fender well but don't rub). The front are a different story 255-35-18 on 18x9 +42 and brrrrrmmmm IS the sound of the fender being pulled out :( . Luckly it wasn't to bad and was able to roll the fenders, so far they haven't rubbed again but I am more careful now (not that I wasn't before but even more now). I will try to post a picture of zoom zoom's car later today but hear is mine. I will try to get a better one later.www.rx good luck Jeff

Can you elaborate on this

More understeer, and slower acceleration, is what Max is referring to. Try a search. Lots of info on this board.

Make sure your car is on an ALIGNMENT LIFT, so that the suspension is loaded. That's the only way to see the clearance from the trailing arms. Actually you don't need a lift just crawl underneath, and check the inside rim lip clearance away from the rear trailing arm.

the picture of zoom zoom's wouldn't post.

I'll try a couple of mine. It has Eibach springs and Koni yellow shocks with the rear on the lowest setting 1 1/2" total and the front on the middle 1 1/4" total drop.[IMG]http://[/IMG]

another, sorry about the poor quality. Some day I need to figure out how to do this right!!:confused: [IMG]http://[/IMG]

:bigthumb: jr426

jr426, what wheels are those? They're NICE! Like the tires too! Glad you didn't skimp, and went with the S-03s :)

Yeah, the front would be better at 9 x 17, 45-mm offset or 49-mm offset...Nice wheels! Are they Volk GTNs?

Love the "look" of wide tires in back :) It is overkill though. Look at the contact patch the 285s make statically with a 50/50 weight distribution, 2750-lb Rx7. The rears tires only have "dirt" just barely past the last set of outer grooves! The outside shoulder edges do not touch the ground! I presume the "unused" outer portions of the 285s "could" be used during road course track events or autocrosses :)

If you ever walk past a 2002 Porsche 996 Carrera 4S. Check out the 295/30-18s (on 11 x 18) that car has. That car NEEDs 295 tires. The engine sits at the ass-end of the car, thus loading the rear tires STATICALLY, so you'll see dirt near the outside shoulders of the 295 tire :)

Yeah, watch out for diameter (rubbing) problems if you go 245/45 or 255/40. Those may be too big for the front depending on your suspension setup.

-Max

You are absolutely right, 285 would not be used to the max hell I'm not using my 275 completely (see pic). 285s would look bad ass but like you said its overkill.

Even with my 17s there is enough clearance with the stock trailing arm, I-arm and toe link to fit probably 295s (see pic) For now I will stick with the 275s or even go down to 265 so I can get the SO3s but if I ever have a few bills to burn I will slap 285 out back :)



BTW 911 GTS has 235 front and 315 out back (80mm diff)

trailing
https://www.rx7club.com/forum/attach...postid=1394439

contact patch :)
https://www.rx7club.com/forum/attach...postid=1394470

same

It also has a rear-heavy weight distribution (42/58?), so it needs wider tires out back. The FD does not have weight distribution like that.

I have had my car setup to understeer a lot and it is no fun on the street. The front just pushes too much, most notably on light to moderate acceleration through or out of a turn. It sucks that way -- no fun. A little bit of understeer is probably ideal for the street for most drivers (me included), but a lot of understeer is an entirely different story.

It does look like you have enough room for wider tires. I wish tire companies made 285/35-17. That would be a great size for FDs. I'd say your current tires are pretty much done! :)

-Max

Yes, they are GT-Ns. 285s are a bit overkill but they had 0 miles on them in that picture so they didn't have a chance to "get dirty" yet. I am keeping an eye on them and will realing as necessary (have 0.8 degree negitive camber on rear). No point in putting that big of a tire on just to use only the inside half. One thing I have learned from my rim buying experance is that Mackin does not know proper fittment for RX7s, it was a 4 month nightmare to get my rims.:mad:

We could have helped you here :)