Wide Auto-x Tires - 245/4X/17

[TurfBurn]

Did a calculation on Miata.net

245/45/16
Sidewall: 4.3"
Radius: 12.3"
Diameter: 24.7"
Circumference: 77.5"
Revs/mile: 817.0

235/40/17
Sidewall: 3.7"
Radius: 12.2"
Diameter: 24.4"
Circumference: 76.7"
Revs/mile: 827.0

Seems like the 16" would be faster but now it comes down to the availbility of tires that you want.

Thanks Jeff. I'm not too concerned about the rotating mass and diameter, right now I am WAY overpowered for the tires and can never full throttle anyway without lighting up on the course. I do have a little concern about losing some turn in response or sensitivity if I get this tire size too wrong, but I'm reasonably confident it'd be okay. I'm just hoping I can get these around the JIC's and also inside the fenders.

 

[moxnix]

Stock rules are size & width must be same. offset within +-1/4 inch (about 6.35mm) so a 45 offset 17x7 would not be legal but a 50 offset would be.

Running 04's was the problem. The 04's were the worst ever for hoosier.

I agree on longevity but size wise hoosier is the better bet right now I think.

My first suggestion would be to try to find somebody with old corded tires in the size you want and try to beg/borrow/steal the tires and some rims to try them out on to check fender/strut clearances. Have you rolled your inner fenders?

 

[xelderx]

I didn't care for the responsiveness of the hoosiers (I was running as304's though at the time) and the wear on them just never matches up to what the Kumho's get for longevity. Also, there have been a number of complaints in our region with Hoosiers of them overheating even when wetted between runs.

A3S04 are nowhere near as good as the new A6. The V710 does last longer as far as tread life, but the usuable grip falls away about as quick as the Hoosier. They are just harder to cord, but not any quicker or longer lasting on a competitive level. I ran V710s in 2005, but went back to the Hoosier when the new A6 came out due to the shorter sidewall for better gearing.

 

[TurfBurn]

I've also heard good things about the BFGoodrich race slick on some reviews and stuff I've checked, and have considered runing those. they come in the same size as the Hoosier. Any feedback on those?

Right now I'm thinkinging I'll work out my measurements and everything points to going to a 17x8 rim with 28 offset being my best bet to clear the struts and still stay tucked inside reasonably well.

 

[moxnix]

Everything I have heard about the BFGoodrich has been that they are more of a track tire than an autox tire.

 

[xelderx]

I've also heard good things about the BFGoodrich race slick on some reviews and stuff I've checked, and have considered runing those. they come in the same size as the Hoosier. Any feedback on those?

Right now I'm thinkinging I'll work out my measurements and everything points to going to a 17x8 rim with 28 offset being my best bet to clear the struts and still stay tucked inside reasonably well.

I can't see how a +28 offset will stay tucked in. My 15X7 +37 rims cause 225 tires to stick out in the back.

http://www.mazdas247.com/forum/attachment.php?attachmentid=103853&d=1174707092

My FD rims are 8" wide +50 offset and they just barely clear the fenders in the back. With a 245 series tire on them I had to grind on the strut and the fender...it still rubs just a hair in the back under hard compression.

 

[Vanimaniac]

I was working corner 3 when you ran. Car looked good. 205's are definitely not enough tire for your car!

Have you looked into the Hankook's? Not sure what kind of sizes they are offering for 16's and 17's though.

$130 a wheel is not bad but at 20lbs each! Yikes.

Van

 

[Jeff@Tri-Point]

I've also heard good things about the BFGoodrich race slick on some reviews and stuff I've checked, and have considered runing those. they come in the same size as the Hoosier. Any feedback on those?

Right now I'm thinkinging I'll work out my measurements and everything points to going to a 17x8 rim with 28 offset being my best bet to clear the struts and still stay tucked inside reasonably well.

Front WHeel

Rear Wheel

This is front and rear clearance with a 235/40/17 tire and 17x8 47mm Offset...

Currently I'm using 17x8 55mm offset and they need a 5mm spacer in the rear to clear the strut... For the fronts I can't lower the car enough with a 8" spring because the tire will hit the lower spring perch, I would recommend possibly using a 7" or 6" spring if you plan on going with that setup....

However the 47 Offset wheels allow the car to go down as far as the swaybar bracket will allow without any rubbing issues of the lower spring perch.

 

[TurfBurn]

The JIC's seemed to screw with the distances a lot once camber is added. With my 215/45/17 tires on a 7.5 rim with 45 offset the rears at 2 degree negative camber I clear the strut body by about 1/8" and clear the rear fender by almost a full inch. The fronts I have all sorts of space in both directions up there.

What are you running for struts? My JIC's may be a large factor in this as the strut mounting holes are slotted so the positioning is different.

I'll take my buddies 245/45/17 setup at +45 offset and see how that fits on the car and work back from there I think.

My option on the rims I'm looking at are +28 and +42. Or I can look for other rims if needed as well...

 

[TurfBurn]

I was working corner 3 when you ran. Car looked good. 205's are definitely not enough tire for your car!

Have you looked into the Hankook's? Not sure what kind of sizes they are offering for 16's and 17's though.

$130 a wheel is not bad but at 20lbs each! Yikes.

Van

Thanks! I had my head up my ass on Sunday though and couldn't sort that course out to save my life. Felt like such an idiot by the end of that day, I know I ran a good 2 seconds off where I should have been.

What were you driving for the weekend?

 

[TurfBurn]

Currently I'm using 17x8 55mm offset and they need a 5mm spacer in the rear to clear the strut... For the fronts I can't lower the car enough with a 8" spring because the tire will hit the lower spring perch, I would recommend possibly using a 7" or 6" spring if you plan on going with that setup....

However the 47 Offset wheels allow the car to go down as far as the swaybar bracket will allow without any rubbing issues of the lower spring perch.

Those both look like a pretty reasonable amount of clearance. what is the strut type and the camber?

 

[Kooldino]

Could the +28s rub the fender in the rear?

 

[Jeff@Tri-Point]

The JIC's seemed to screw with the distances a lot once camber is added. With my 215/45/17 tires on a 7.5 rim with 45 offset the rears at 2 degree negative camber I clear the strut body by about 1/8" and clear the rear fender by almost a full inch. The fronts I have all sorts of space in both directions up there.

What are you running for struts?

I'll take my buddies 245/45/17 setup at +45 offset and see how that fits on the car and work back from there I think.

These are the Protege stock strut bodies, you should take the JIC and see if the mounting holes are the same distance at the lower mount from the body to the upper pinch hole.


I'm running 3 3/4 of negative camber in the front and ~2 3/4 of negative camber in the rear.

 

[TurfBurn]

Could the +28s rub the fender in the rear?

Yes, very likely, but that is what is trying to be figured out.... If I can get away with some rolling and some other tweaking to get it down to minor rubbing, then so be it. Or if I have to run a 225 in the rear then so be it as well.... but I'm trying to get to 245's all around. Jeff looks like he got some reasonable clearance on some 235's though, so I'm thinking I can weasel a little more with some creativity.

 

[TurfBurn]

These are the Protege stock strut bodies, you should take the JIC and see if the mounting holes are the same distance at the lower mount from the body to the upper pinch hole.


I'm running 3 3/4 of negative camber in the front and ~2 3/4 of negative camber in the rear.

I know that the mounting holes are not in the same spots. My car was all sorts of fubar when I first put them on. I actually couldn't even fit the tires I had been running up to that date (with spool springs and stock shocks). I disassembled the JIC's and re-milled them myself to get things to fit. So I think my geometry is a fair bit different than you guys so it is going to take some funky measuring to get this all to work and may be why my offsets are so different.

For example, as I said on the rears, with my 215/45/17 tires on the 7.5 rim with a 45 offset I have less than 1/8" clearance at -2 degrees. Going to 2.5 degrees was straight up contact with the strut body. I want to get the rear camber to -2.5 with the front at -3.5 (just a little off from you Jeff, which makes me feel good about how I'm setting that from what I've seen on pyrometer temperatures). But I need additional offset space to achieve that. So based off that calculator I'm using online, the 28 offset would give me an extra .43" of which about .300 would be eaten up by the extra tire sidwall. So it would give me about what I need to get a little more than -2 at the rear and be just barely off the shock body.

I also know, that up front on those same rims/tires I contact the inner wall (engine bay) with the tire at the back (left turn for left tire, right turn for right tire), so I also know I'm tight for those.

 

[Jeff@Tri-Point]

Yes, very likely, but that is what is trying to be figured out.... If I can get away with some rolling and some other tweaking to get it down to minor rubbing, then so be it. Or if I have to run a 225 in the rear then so be it as well.... but I'm trying to get to 245's all around. Jeff looks like he got some reasonable clearance on some 235's though, so I'm thinking I can weasel a little more with some creativity.

I've also fit 245/40/17's all the way around, the rears have a little bit of clearance from the strut, maybe 3/32 of an inch, hard to say, I've never measured.

 

[TurfBurn]

If it clears it clears. So I guess the important point there is that it CAN be done, I just have to figure out the offsets and spacer combos for my situation along with tweaking the fenders a bit to get the space. I guess until I fit my buddies rims and see where they fit up I won't be able to get much further on this.

 

[Vanimaniac]

Thanks! I had my head up my ass on Sunday though and couldn't sort that course out to save my life. Felt like such an idiot by the end of that day, I know I ran a good 2 seconds off where I should have been.

What were you driving for the weekend?

I was supposed to tire warm my buddy's DStock Lexus IS300. But I got traded for another tire warmer (plus a first round draft pick (doh) ). I ended up running an XP Honda Civic! 260whp, 2000 lbs. My practice in that car consisted of driving from grid to start line. (spank) Too much car for me. I could have gone a lot faster if it had like 100 less hp. Anyways, I too drove a full 2 seconds slower than what I was supposed to on Sunday. It seems most guys ran about a second slower on Sunday. I ran 3 seconds slower on my fastest run (hit the start cone) and 4 seconds slower on my only clean run. (boom07)

Good luck with your tire setup. My suggestion...... go big or go home.... run flares and throw some 285/30/18's on that bad boy!

Van

 

[Macs MSP]

So they were running illegal wheels for stock class? Guess it is a good thing they can't drive.

First off I want to clear something up. I am by no means running an illegal offset on my MSP. There must have been a confusion in the conversation between Steve and I about the offset I was using for autocross and my daily driving wheels. For autocross I run a 50+ offset front and back with 245/40 Hoosier A6 up front and 225/40 (sometimes 225/45) in the rear. I stated that for my daily driving tires I run the Bridgstone RE01 245/40 front and 225/45 in the rear with a 45+ offset. I know what the rules are and I'm not going to bend or brake them.

Second, moxnix, any time you want to co-drive my MSP and see what kind of driver I am you are more than welcome. You might want to check out who you are talking about before you state who can or can't drive. We had a lot of issues with the car in Milwaukee because the car was set up completely different than what it was before. I'm not afraid to try something new just to see what will happen. It's all about one race, and that's Nationals. Every race before then is a test and tune.

Brian

 

[moxnix]

First off I want to clear something up. I am by no means running an illegal offset on my MSP.

I am glad you are able to clear that up.

As for your kind offer of a codrive I would love to but I don't think I will be out in your area anytime soon. If you happen to be in the DC Area I'll be glad to let you try mine out but it is not quite as well sorted as yours is right now. I am hoping to actually have it running by this weekend.