Tires/Setup Questions

[Midnightsky]

Last Wednesday I re-learned a valuable lesson in autocross, looking/planning ahead.  In conjunction with that I have been taking a deeper dive into the setup on my 2017 Mazda 3 in preparation for next season which I plan to attend 70-80% of the events.  The decision has been made to add RE71's to the car for next season, I want the grip.  My goal is to remain in H-street but Im not afraid to step up to STS if the benefits can be argued into the PAX time.  My oem wheel size is 18inch and with tire pricing Id like to drop to 17inch wheels.  Now Im told the RE71's fit wider than most tires and as such you need a wider wheel or narrower tire width choice.  I would like to have 225/50/R17 RE71's but from what I can gather I would likely need 17x8 wheels(or wider?) and that might break my budget.   Is it worth spending the extra money on wider rims to accommodate the wider RE71 size I want, or should I just stick with 17x7 rims and drop to a 205/50/R17 size?  Obviously I will need to keep within a +/- 5mm offset for all this if I plan to remain in H-street for the awesome pax adjustment but to accommodate the grip I am looking for with some possible changes to front and rear camber/toe I may just have to step up to STS.

What do you guys think?

[zero10]

A quick note - you cannot change wheel widths in HS, so you need to keep the width of the factory wheels but can up/downsize 1 inch in diameter.  So if the factory wheels are 18x7 then you can do 17x7 only.

I have personally crammed 225/45R15 tires onto 15x5.5" wheels - though you are going to have a lot less sidewall so that might restrict how far you can pinch them.

My advice would be to stay in HS as long as possible.  I moved to STF and regretted it.  I made the change while chasing more front camber in an effort to reduce tire wear, I never found enough camber and wish I had just stayed in HS.

[Midnightsky]

Ok that makes sense, I will stick with 17x7 rims with 205/50/R17 RE71's and hold within H-street next season.   Maybe I can get Cam to fiddle with my oem alignment and possibly gain a tiny bit of help there.  Rear swaybar and adjustable endlinks were just ordered so I should have that in place for the September YYC event. 

[Robp201]

Last Wednesday I re-learned a valuable lesson in autocross, looking/planning ahead.  In conjunction with that I have been taking a deeper dive into the setup on my 2017 Mazda 3 in preparation for next season which I plan to attend 70-80% of the events.  The decision has been made to add RE71's to the car for next season, I want the grip.  My goal is to remain in H-street but Im not afraid to step up to STS if the benefits can be argued into the PAX time.  My oem wheel size is 18inch and with tire pricing Id like to drop to 17inch wheels.  Now Im told the RE71's fit wider than most tires and as such you need a wider wheel or narrower tire width choice.  I would like to have 225/50/R17 RE71's but from what I can gather I would likely need 17x8 wheels(or wider?) and that might break my budget.   Is it worth spending the extra money on wider rims to accommodate the wider RE71 size I want, or should I just stick with 17x7 rims and drop to a 205/50/R17 size?  Obviously I will need to keep within a +/- 5mm offset for all this if I plan to remain in H-street for the awesome pax adjustment but to accommodate the grip I am looking for with some possible changes to front and rear camber/toe I may just have to step up to STS.

What do you guys think?

I run 225/45/17 on a 7" rim and it seems to work fine.

[JamesTCallaghan]

I've seen a 245/40/17 on a 17x7 wheel before.

[MurrayPeterson]

My Miata has 17x7 wheels, and 225 fits fine.  However, I dropped down to 215 width and have seen no change in performance.

I agree with the others -- stay in HS.  ST* classes require a huge investment to be competitive, and a partial prep for the class will never work.

[Midnightsky]

Another quick question, when I get a rear swaybar installed end of the month, should I be asking to have my oem alignment tweaked as best it can within the oem specs? I doubt its worth much so is it even worth it?

[MurrayPeterson]

The alignment question is one I can't answer.  You need to research more to see what can be done (within the rules of course).  Our Mazda 3 has no alignment adjustments whatsoever on the front, so toe-in is the only thing that can be done.

[Reijo]

Alignment is worthwhile .... even without adjustments you can still loosen all the mounting bolts and get some extra negative camber which will give better performance and less tire wear on the track.

R

[Reijo]

Alignment is worthwhile .... even without adjustments you can still loosen all the mounting bolts and get some extra negative camber which will give better performance and less tire wear on the track.

R
[/quote

Actually if you can't tell the difference, then maybe you should also be taking more schools to increase your driving skills.  You can always use a school to better yourself.

R

[Midnightsky]

Alignment is worthwhile .... even without adjustments you can still loosen all the mounting bolts and get some extra negative camber which will give better performance and less tire wear on the track.

R

Actually if you can't tell the difference, then maybe you should also be taking more schools to increase your driving skills.  You can always use a school to better yourself.

R

Ideally I want to take 3-4 schools in the next couple years if I can fit it into the budget.  I have more racing seat time on loose surface than I do on pavement so the desire is there to balance out that knowledge and experience. 

For the alignment I'll talk to Cam and have him fiddle with it while the swaybar is being installed. Any amount of negative camber up front would be nice for turn-in, a little toe can't hurt either.

[E6Cueman]

I've seen a 245/40/17 on a 17x7 wheel before.

I did this once, but every set since has been 225/45.

[JCS]

My Miata has 17x7 wheels, and 225 fits fine.  However, I dropped down to 215 width and have seen no change in performance.

I agree with the others -- stay in HS.  ST* classes require a huge investment to be competitive, and a partial prep for the class will never work.

This is true.  Although you'd be STF not STS which isn't a huge penalty I think at 0.800 Pax.

If I had my time over I'd go with the spring/koni combo instead of the coilovers and stay in HS.

[JamesTCallaghan]

I've seen a 245/40/17 on a 17x7 wheel before.

I did this once, but every set since has been 225/45.

Yeah I don't think there was any benefit over a 225.

[Midnightsky]

I am having a dilemma of sorts, my oem offset is 50mm, and I am debating if I should try to find something with a 55mm offset to try and bring the grip a bit wider for autocross.  Does it make that much of a difference? Most of the rims Im finding have a 45mm offset, if I want to retain the 50mm offset there are some previous gen Mazda 3 rims that were 17x7 with a 50mm offset.   Im sure I am probably just nit picking over nothing and should probably just worry about that loose nut behind the wheel lol.

***edit***

I think I may have found my compromise for an autocross only wheel, NC Miata wheels, 17x7 5x114.3 and 17lbs.......anyone have a set laying around?