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Tire size question for Auto X

2K views 12 replies 7 participants last post by  M-bird 
#1 ·
I want to stay with street tires and have decided to get the Azenis sports. I am torn between the
1) 225/45 size on OEM 17" sports package rims.
2) 245/45 size on the same rims

Question 1. Anyone tried 245/45 Azenis sports all round on OEM rims? Will they fit?
Question 2. I know I'll get 4% higher gearing with the 245/45-17s, but at same time I would gain 8% contact patch. Which do you think is more important, the 4% gearing ratio or the 8% increase in contact patch?

Thanks in advance!!
 
#2 ·
Luke said:
I want to stay with street tires and have decided to get the Azenis sports. I am torn between the
1) 225/45 size on OEM 17" sports package rims.
2) 245/45 size on the same rims

Question 1. Anyone tried 245/45 Azenis sports all round on OEM rims? Will they fit?
Question 2. I know I'll get 4% higher gearing with the 245/45-17s, but at same time I would gain 8% contact patch. Which do you think is more important, the 4% gearing ratio or the 8% increase in contact patch?

Thanks in advance!!
You will hate the 4% gearing loss. How about a 235/40/17 Yokohama ES100? They aren't know for their long term road manners but they are quieter and better in the rain than the Falkens. I'm currently running the ES100s on my E30 for track and autocross use.



Ed
 
#3 ·
The auto-X where I run is really harsh on tires and chunks narrow block tires really bad. Keep in mind that my car weighs 3400 lbs (E46 wagon). I've actually tried both tires before and the Azenis Sports are really a notch above the ES100. I will mount these tires on rims dedicated solely for the track, so quiet and wet performance are not an issue. Great suggestion for a road/track tire though. I don't want to move to R compound tires as it will move me up a class.

teamdfl said:
You will hate the 4% gearing loss. How about a 235/40/17 Yokohama ES100? They aren't know for their long term road manners but they are quieter and better in the rain than the Falkens. I'm currently running the ES100s on my E30 for track and autocross use.



Ed
 
#4 ·
245/45 on 7.5" rim...

yes i tried this on accident....

its a long story but when i picked my car up when it was first
delivered it had the 8.5" in the trunk as a spare and three 7.5"s
on the car...

i did not notice this when the sidewall blew out on one (ill let
you guess which) of my 245/40 continentals after ~17k miles.

same thing happened to the 245/45 falken only more violent.

both tires were close to the wear bars when they died so it was
not like they had not had pretty good useful lives.

i think these would work great for you only for autocross but i
would not recommend them for daily driving. i run 255/40 kuhmo
victorracers all around on the 7.5" and 8.5" wheels. If you are
going to have dedicated race rubber i recommend r tires unless
you want to be in a street tire class...

the falkens were great in the rain for me. less hydroplaning
than the contisports! they did get noisy at the end of their
life...

take care
 
#5 ·
I run 16's for autocross

I run 16's for autocross, they are cheaper and give me better acceleration and lower weight. I have some z3 rims that are 8.5 inches wide and i run 225/50/16 kuhmo v700 victoracers. They are R compound and they are durable and are miles ahead of the non-R compound tires.

jme
 
#6 · (Edited)
Luke said:
I want to stay with street tires and have decided to get the Azenis sports. I am torn between the
1) 225/45 size on OEM 17" sports package rims.
2) 245/45 size on the same rims
Azenis are a good choice. On a 330ci last year the winning car at Nationals ran on 255/40x17 Victoracers...so the 245's will fit. Also, if you have not found it, the tirerack site and/or manufacturer gives overall tire dimensions for you to compare....

The gearing issue you'll notice more with street driving than in autoxing. 235/40 is a nice size, but I know not always available.

The other thing to consider, especially if it's a rough lot...is the the Azeni's tend to get a bit greasy/slippery when they get too hot...check with other competitors who run them there. What I'm thinking is that the larger sized tire may help avoid this overheating and the tires going away just when you need that final 2 tenths on that last run?
 
#7 ·
Mike48162 said:
Azenis are a good choice. On a 330ci last year the winning car at Nationals ran on 255/40x17 Victoracers...so the 245's will fit. Also, if you have not found it, the tirerack site and/or manufacturer gives overall tire dimensions for you to compare....

The gearing issue you'll notice more with street driving than in autoxing. 235/40 is a nice size, but I know not always available.

The other thing to consider, especially if it's a rough lot...is the the Azeni's tend to get a bit greasy/slippery when they get too hot...check with other competitors who run them there. What I'm thinking is that the larger sized tire may help avoid this overheating and the tires going away just when you need that final 2 tenths on that last run?

Azenis + hot day = garden spray (a must)

My last autox I attended I would run right at the competitive times until the last two turns where the car would spin (even with less speed). As soon as I started spraying down the tires, no more spin and more grip. I was running 4 245/45/17.

As for the gearing change, you will notice it and you will hate it. My autox car is my M Coupe which is lighter and has more hp than the 325i/it.

I can tell you that the larger size tire wont help with the overheating issue during the summer. At least in the Central CA summer where upper 90F is common. The last event was at Atwater where the national tour runs so it was pretty rough on the tires. Me and my co-driver both noticed the tires over heating after our 2nd run (out of 5).

I will say that if the plan is to run Azenis for autox only then go for it. They are cheap enough that you can use them for one season and then buy new ones at the start of the new season. I'm pretty sure my tires wont last more than one season.
 
#9 ·
teamdfl said:
Anyone autocrossing the Goodyear GS-D3 yet? It comes in E46 friendly 235/40/17 and 245/40/17 as well as a shorter 245/35/17. They are more expensive but guys seem to like them on the street.

I was tempte to try those. Except I talked to a seasoned autoxer and he told me they have the same problem as the Toyo T1-S I was running at the time. The shoulders are very soft and they wear out very quickly compared to the rest of the tires. Thus you end up throwing them away with plenty of tread on the inside and nothing on the outside shoulder.

My old toyos had 75% thread left in the inside/center and 0 on the outside shoulder. This was with -2.4 camber. The rears were nice and even with -1.2 camber.
 
#10 ·
WOW, I had almost given up on this post when 'suddenly'

I get so many replies. Thanks for the great information!!

Just a few notes. My rims are 8" all the way round since they are the 323 sports package (sorry I didn't clarify). Also, I am currently running on the Azenis sport tires, but unfortunately very undersized at 205/55-16 . These are left over tires from a VW GTi that I used to Auto-X. It is true that these tires get slimy after 3 runs in the morning and 2 in the afternoon. My last 1-2 runs feel like I riding on greese...and it doesn't help that the wagon is heavy.

I unfortunately will likely be running in 100+ degree heat in Texas until Fall arrives.

Slick tires:
I'm currently running competitively in my class right now with street tires (Azenis), however, to be competitive in the next higher BMW class, I need to shave 3-4 seconds over an 80-100 second course. I think I'll find that really tough since I'll be runnning with 328s, 330s, Z4s and stock M3s.

The course typically hits 70+ mph on 1-2 stretches and best time of day is usually in the 80-100 second range.

For the guys who have switched from good street tires to R compound, how many seconds do you typically pick up per 60 seconds of racing? thanks in advance!!
 
#11 ·
I haven't switched to R compounds yet. Next year I might be ready for Toyo RA-1.

Most people say that R compounds are good for about 2 seconds on a 60second course, but you wont see that benefit right away. You have to learn to use the extra grip. When I switched from Toyo T1-S to Azenis there was a whole lot more grip and I had to relearn the car. took about 4 events.

Also going from Azenis to R-compound isn't a big a difference as other street tires to R-comp. Azenis are damn close to R-comps already. If you go with Hoosiers then there will probably a bigger difference but the Toyo and the Kumho R comps wont show that much difference in grip.

However, both the kumho (victoracer) and toyo r comps will work great when hot :)
 
#12 ·
New tires...1/2 way there?

For the guys who have switched from good street tires to R compound, how many seconds do you typically pick up per 60 seconds of racing? thanks in advance!![/QUOTE]

Driven well the new tires should get you 1/2 way to the fast competitive times. R tires respond more quickly with less aural feedback. Takes some getting used to. While R tires offer more grip in corners and transitions, they may not offer the same noticeable advantage under braking...

R tires offer a faster way around the course, but also more chances to lose time when we bobble. Keeping up with the fast boys for me seems to be less about finding out how to go faster, but more about not finding ways of adding extra time out there (i.e. by being too far off slalom cones, by taking too wide a line in a corner, by trying to go too fast in a slow section etc)
 
#13 ·
Mike48162 said:
For the guys who have switched from good street tires to R compound, how many seconds do you typically pick up per 60 seconds of racing? thanks in advance!!
Driven well the new tires should get you 1/2 way to the fast competitive times. R tires respond more quickly with less aural feedback. Takes some getting used to. While R tires offer more grip in corners and transitions, they may not offer the same noticeable advantage under braking...

R tires offer a faster way around the course, but also more chances to lose time when we bobble. Keeping up with the fast boys for me seems to be less about finding out how to go faster, but more about not finding ways of adding extra time out there (i.e. by being too far off slalom cones, by taking too wide a line in a corner, by trying to go too fast in a slow section etc)[/QUOTE]

Dot-R tires are generally good for 1 second faster for every 18 seconds onm course.

For a car that heavy for street autocross tires go with BFG KD (not KDW) or Kumho Ecsta MX

The Azenis hate heat, and for a street tire you want the lower gearing.

For a Race tire you want a Hoosier , a 245/45/16 A3S04 would be a good place to start.
 
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