ExpensiveHobby22

I just picked up my car yesterday. The car has 17x9 wheels on it and the tires are wasted. Right now it has 225/45s on the front and 235/45's on the rear. From what I've read in the archives a lot of people like to run 235/45's in the front and 255/40's in the rear. Is the handling that much better than just running 235/45s or slightly bigger on all 4 corners? Does the performance outweigh the extended treadlife you could get with being able to rotate the tires? Suggestions?

Also, given the same basic tire design from a given company is their Z rated tire better than the WR as far as grip goes?

Thanks,
ray

kdamer

1) Yes, the difference in cornering is noticeable with 235 front, 255 rear. This combo will induce a bit of understeer, but that's easily correctable with the throttle.
2) the Z and WR ratings do not refer to treadlife. They refer to speed ratings. I can't remember what the actual numbers are (Z=149mph, WR=168?), but they do not relate to treadlife. There is a treadlife rating for tires, but each manufacturer uses it differently, so there's really no easy way to compare between manufacturers.

ttb

http://www.tirerack.com/tires/tirete...eral/speed.htm

dont think the speed rating has anything to do with the gripping, although it's natural to assume that the higher the speed rating the more grip the tire will be.

ExpensiveHobby22

Yeah, that's what I think too. I've read all the info on those sites. I'm just curious because the price difference between z rated and wr in the same tire family is significant. Trying to decide if I should save some money.

Thanks,
ray

ttb

if you're looking for tires i've heard the s-03 are great.

maxcooper

How do you know the wheel size? I only ask because it is often miscommunicated or misinterpreted. I have even heard of wheels with two different size stickers on them. 225 seems narrow for a 9" rim, so that leads me to suspect that they aren't 9". Note that an 8" rim will measure 9-9.25" from rim edge to rim edge.

-Max

ExpensiveHobby22

Good point. I measured them a little over nine from outer edge to outer edge. Maybe they are 8's, although the front tires do look a little small for the wheel.

However I'm still really curious about the different sizes front and rear vs 4 of the same size. Does the handling outweigh the costs (More initial cost + reduced life because you can't rotate)?

I know it all boils down to what you want for your particular car but any enlightenment would be great.

Thanks again,
ray

ttb

there's a few threads about staggered setups, search for "staggered", "oversteer", "understeer."

ExpensiveHobby22

Cool. I couldn't figure out what search words to use.


ray

maxcooper

I would bet they are 8" based on your measurements. 235/45-17 or 245/40-17 is what I recommend F&R. Both work on 8" rims just fine. 255s are too wide. You can get S-03s for relatively good prices these days. I'v been happy with mine.

-Max

ExpensiveHobby22

Sorry I'm asking so many questions. I wasn't counting on having to buy tires mere days after getting the car. I guess my thoughts on "the tires should be replaced soon" and the previous owner's are way different.

Tirerack has the old AVS intermediates on sale for 70ish. I think I may go with these despite their short lifespan. I was hoping the cars would last for awhile since I need to buy winter tires for my Jetta as it's now the designated winter car.

So, what kind of offset/backspacing would my wheels have to have to run 245/40s on all 4 corners? I'll have to measure that tomorrow.

Thanks,
ray

maxcooper

No problem on the questions.

How much space do you have now? It isn't a perfect way to do a fitment, but look at the difference in tire sizes on the spec sheets and try to imagine if they will fit or not. Will it rub anything as the car sits, or will the new tires be more likely to grab the fenders on suspension jounce? (You don't have to answer these on the forum, but these are some questions you can ask yourself as you look at your setup on the car.)

We can probably help guess the offset from the backspacing measurement and that should help people respond with their experiences.

-Max

ExpensiveHobby22

I went out and remeasured the wheels. I get 9.25 for the wheel width (outer edge to outer edge) and 5.6875 for the backspacing. That works out to 1.0625 in. (26.9875mm) offset right?

Based on this can you guys give me some suggestion as to what will fit.

Also, I think the S-03's are out of my price range right now. What are some tires that are still good that cost less. I have experience with Kuhmo Ecsta Supras on my Jetta, and I have liked them. How do they perform on an RX-7?

Thanks again,
ray

SleepR1

CORRECT! I'm impressed. One of the few posters that knows how to crunch offset, back space, front space numbers (there are only a handful of Rx7 Forum members that I know of that can do that).

With that said, that's an awful wacky fitment. You're really maxed out with the front space measurement at 3.56 inches for the front wheel positions (FD Rx7). Typcially you want to stay within 3.5-inches with that dimension to keep from rubbing the front fenderlips. The odd thing, is that you have all that back space clearance. The previous owner was going for maximum track width, apparently?

My guess is that your bead-to-bead rim width (nominal) is 8.5-inches. To maintain optimum clearance from fender lips, I'd choose a 225/45-17 for the fronts. You could go 245/40-17s in back, assumeing the rears are the same widths and offsets?

ExpensiveHobby22

Thanks for the info. The rear wheels are indeed the same size as the fronts. I'll probably try the fitment route that you suggested.

Thanks for the compliment too. I tried to read up on tire info as much as possible before posting. Obviously I missed a few things though.

Thanks for all the help. Any more ideas/opinions would be welcome too.

ExpensiveHobby22

I forgot to ask in the previous post. Do you think I could manage 235/40's in the front? And how would these look on the rear?

I ask this because Tire Rack has a closeout on the old AVS Intermediates in this size for 63 bucks and that is hard to pass up. I know they don't last very long.

Just looking for opinions. I still haven't decided what to do and am not set on any one thing.

Thanks
ray

SleepR1

Yeah, sure you can do that. The '95 M3s run that size all the way around with 7 x 17 wheels, so no doubt you can fit 235/40-17 on 8.5 x 17 wheels. There might be some concern with load index, but the BMW M3 is heavier than our Mazda Rx7s (FD), so...

I'm currently running 255/40-17 Yokohama AVS Intermediates myself (on 9 x 17 SSR Integral A2s, 45-mm offset), and fully intend to get another set of five AVS I's (I run a full size spare that I rotate into use). The Rack has the 255/40-17s for $94 each.

I've had excellent results with the AVS I's. They're an outstanding road tire--quiet, smooth, sticky, decent wet traction; and the AVS I's also make outstanding drivers education event tires. No they don't deliver Hoosier R3S03 grip, but the AVS I's are good enough to satisfy my need for full-on driving on a high speed road course, wet or dry conditions.

In short--I highly recommend the AVS I's, especially at the Tire Rack's closeout pricing!

ExpensiveHobby22

Cool. I'm counting on the worst case scenario where my wheels are 8.0 so I don't think 255/40s would fit them well, right? And there is no way I could fit them in the front, so I'd have to stagger? I'd love it if they did fit the whell so I could at least throw them on the back.

If I did end up having a 8.5 inch wheel would they fit inside the fenders with the strange offset I have?

My friend ran AVS I's on his 944 and raved about them except for their treadlife, which I can deal with since I have another car.

I guess I'll research more into the load index and try to find out what kind of wheels my car actually has.

Thanks,
Ray

ARD T2

iTrader: (22)

Ray, if you let me know what wheel it is or just post a picture I might be able to get you a definte answer on that wheel's printed offset.

Or we could pop one wheel off real quick and look at the stampings on the inside. Look for the diameter x width. and ET35 or ET27 or something like that.

For some reason it sounds very out of pattern with the offset and width you've mentioned. So some wheel brand and model or a pic and the answer should be easy to source for me. I know Manny must be scratching his head the same way I am. From calcs sounds right but just kinda weird.

See ya, Rishie

ExpensiveHobby22

This is the best pic I have of the wheels so far. I'm going to take one off later today to see what it says behind the wheel. They are one of those multi-bolt pattern wheels.

ExpensiveHobby22

Alright, I pulled a wheel, and it yielded some good information. Mainly, that I should have done this first. They are Kosei 17x8 wheels with a +35mm offset.

I also figured out why I was coming out with that wacky offset number. I was measuring from the inner edge of the outer side, not the last part of the wheel where it touches the tire. This was another .25 inches out. I redid the calculations and came out with the right answer.

So, based on this 255/40s are too wide for the wheel?

If so I'll just go with the 245/40s AVS I's all around for the time being because of the great price and start saving up for the next set.

I also noticed that I could wobble the wheel on both sides a little bit. I'm guessing this is not normal and that my bearings are worn or the axle nut is loose (assuming the rear bearing setup is like a fwd setup).

Thanks again,
ray

ARD T2

iTrader: (22)

As for running that size up front I believe that you would rub. I would suggest what you had running on there before.

225/45 and 245/40 in the rear or something. Basically the post 96 E36 M3 setup.

Rishie

ExpensiveHobby22

Oh well, I guess I will pass on the AVS I's. I really don't want to end up rubbing.

Can you guys give me a rundown of your best picks for tires in the 90-110 range? I want S0-3's, but I can't swing them just yet.

Thanks for all the help.

ARD T2

iTrader: (22)

Yokohama AVS ES100 or Dunlop FM901. Dunlop is stickier.

rishie

ExpensiveHobby22

I talked to Tire Rack today and they said the 235/40 17s would fit the front. Is what they say usually true?

thanks,
ray