R-compound tire recommendation?

[bimmer freaks]

I have 15X7 Team Dynamic rims and was wondering what size r-compound tire will fit? I was hoping to squeeze on some 225/50/15 hoosiers, but was not sure if they would clear. Also what's better - 225/45/15 or 225/50/15 or go with 205/50/15? Any opinions are welcome. This will be for an autox car. How about a staggered setup? Thanks.

[JGood]

How about a staggered setup? Thanks.

Everyone says to stay away from staggered, but ever since I went from 225/50/14 rear & 205/55/14 front to 205/55/14 all around, I get more inside-rear wheel spin on autox courses. It didn't seem to make the car push any more with wider rears either.

This was with V710's.

[joshh]

An 8" wheel would obviously be better but there's nothing wrong with putting a 225 50 15 on a 7". And I would go with the 225 for sure. 710's last way longer than Hoosiers so I'd also go with those.
I'll be trying a staggered set up this year but on my Integra and the opposite of the wides in the rear.

[bimmer freaks]

thanks

Thanks for the opinions...JGood, do you have an open diff or LSD? I am really considering 225's in the rear and 205's up front. I am running IE3's and billy sports on Azenas right not and it is ok. The azenas are getting worn and will need replacement in the future....I just am dying to try out some r-comp tires...so you guys like th 710's....hmmm, I had my heart set on the hoosiers, but might reconsider...thanks again.

[joshh]

If you have the money get the Hoosiers. But expect anywhere from 20-70 runs on them before they wear out. No joke.
A local member hear corded a set of Hoosiers in one day with his EVO.
The Hoosier has awesome turn in but will let go very quickly if you get the tire past their grip level.
The 710's are great because they are as predictable as a very good street tire yet they last 2-3 times longer than the Hoosier. The 710's don't have quiet as much overall grip but are just as good or better in other ways. Let alone cheaper.

[Bruce Colby]

I have a couple comments but no real answer to your question. If you put on tires with a lot of grip, you'll generate a more body roll in the corners, more dive on braking and more squat on acceleration, than you had using tires with less grip. If you get a lot of lean/dive/squat, the contact patch will become less than optimal. You may be able to make camber changes as a workaround for cornering but you can only go so far in the front before you'll start to mess up your braking. And if you have a lot of power, too much negative camber in the rear will impact traction on acceleration. Stiffer sway bars will help control roll; stiffer springs will help control roll, dive and squat. Stiffer springs may also mean you need to alter the damping (shocks) if you want to avoid bouncing around and losing traction. It's can be a vicious/expensive circle.

You also need to consider what you are doing. AutoX needs tires which are consistent from run to run. Track tires require a significant workout in order to get warmed up to the point where they work properly. Consequently track tires tend to change a lot from run to run at autox's so they may not be your best bet. Something like a Toyo RA1 or the very similar Nitto NT01, might be a good compromise. There are some very sticky/soft tires, Hoosier makes some and so does Kuhmo which might be better for autox but it might depend on how close together your runs are.

Big tires are not always the best tires. Bigger tires are heavier than small ones so they add rotational mass and this reduces acceleration (and deceleration). Bigger and/or wider rims tend to do the same thing. If you have enough torque to spin up heavier tires/wheels and enough brake to slow them down, go for it. But remember that the rubber needs to stay properly planted on the the road surface in order to work effectively.

Heavier tire/rims also increase unsprung weight. A big increase in unsprung weight can have an pretty nasty impact on your car's handling if the course is bumpy.

In a perfect world, more/stickier rubber would always mean faster times but it doesn't work that way. It's all about finding the right compromise.

[alex]

I have 15X7 Team Dynamic rims and was wondering what size r-compound tire will fit? I was hoping to squeeze on some 225/50/15 hoosiers, but was not sure if they would clear. Also what's better - 225/45/15 or 225/50/15 or go with 205/50/15? Any opinions are welcome. This will be for an autox car. How about a staggered setup? Thanks.

Go same size as you will be able to rotate tires for longer life.

I'd get 225/50 for your setup.

Alex.

[markseven]

I have a couple comments but no real answer to your question. If you put on tires with a lot of grip, you'll generate a more body roll in the corners, more dive on braking and more squat on acceleration, than you had using tires with less grip. If you get a lot of lean/dive/squat, the contact patch will become less than optimal. You may be able to make camber changes as a workaround for cornering but you can only go so far in the front before you'll start to mess up your braking. And if you have a lot of power, too much negative camber in the rear will impact traction on acceleration. Stiffer sway bars will help control roll; stiffer springs will help control roll, dive and squat. Stiffer springs may also mean you need to alter the damping (shocks) if you want to avoid bouncing around and losing traction. It's can be a vicious/expensive circle.

You also need to consider what you are doing. AutoX needs tires which are consistent from run to run. Track tires require a significant workout in order to get warmed up to the point where they work properly. Consequently track tires tend to change a lot from run to run at autox's so they may not be your best bet. Something like a Toyo RA1 or the very similar Nitto NT01, might be a good compromise. There are some very sticky/soft tires, Hoosier makes some and so does Kuhmo which might be better for autox but it might depend on how close together your runs are.

Big tires are not always the best tires. Bigger tires are heavier than small ones so they add rotational mass and this reduces acceleration (and deceleration). Bigger and/or wider rims tend to do the same thing. If you have enough torque to spin up heavier tires/wheels and enough brake to slow them down, go for it. But remember that the rubber needs to stay properly planted on the the road surface in order to work effectively.

Heavier tire/rims also increase unsprung weight. A big increase in unsprung weight can have an pretty nasty impact on your car's handling if the course is bumpy.

In a perfect world, more/stickier rubber would always mean faster times but it doesn't work that way. It's all about finding the right compromise.

This is really good info.

[Jeremiel5]

This is really good info.

+1923419485207987520398752, thanks for the info! :D

[Jean]

+1 and another 1+ on the tire rotation issue.

There is also another good AutoX dot R tire out there now, lots of guys trying it out, BFG r1.

[Lance Racing]

I agree...

same size to maximize tire life.

Will you be shaving the tire? Shaved vs. unshaved makes a big difference in adhesion. I would think hard core Auto-Xers are shaving to 2/32.

I run 225-50-14 on my race car and run great. I think there are better Auto-X tires than a Toyo RA1. I run the RA1 on the race car, but that is on a road course for 30 minute sessions and they do take a lap to warm up. I shave to 4/32 for a dry track. I keep another set of full treads for a rainy track.

[bimmer freaks]

.

thanks for the replies.....I am leaning towards 225's all around. Not sure what tire to get yet. I am in south florida where the pavement gets very hot, but I think I may go with a used set of A6's or the kuhmos...thanks

[alex]

IBig tires are not always the best tires. Bigger tires are heavier than small ones so they add rotational mass and this reduces acceleration (and deceleration). Bigger and/or wider rims tend to do the same thing. If you have enough torque to spin up heavier tires/wheels and enough brake to slow them down, go for it. But remember that the rubber needs to stay properly planted on the the road surface in order to work effectively.

Also consider change in overall diameter and consequent effect on max speed and acceleration, especially if diff choices are limited.

[tdfox]

I have a couple comments but no real answer to your question. If you put on tires with a lot of grip, you'll generate a more body roll in the corners, more dive on braking and more squat on acceleration, than you had using tires with less grip. If you get a lot of lean/dive/squat, the contact patch will become less than optimal. You may be able to make camber changes as a workaround for cornering but you can only go so far in the front before you'll start to mess up your braking. And if you have a lot of power, too much negative camber in the rear will impact traction on acceleration. Stiffer sway bars will help control roll; stiffer springs will help control roll, dive and squat. Stiffer springs may also mean you need to alter the damping (shocks) if you want to avoid bouncing around and losing traction. It's can be a vicious/expensive circle.

You also need to consider what you are doing. AutoX needs tires which are consistent from run to run. Track tires require a significant workout in order to get warmed up to the point where they work properly. Consequently track tires tend to change a lot from run to run at autox's so they may not be your best bet. Something like a Toyo RA1 or the very similar Nitto NT01, might be a good compromise. There are some very sticky/soft tires, Hoosier makes some and so does Kuhmo which might be better for autox but it might depend on how close together your runs are.

Big tires are not always the best tires. Bigger tires are heavier than small ones so they add rotational mass and this reduces acceleration (and deceleration). Bigger and/or wider rims tend to do the same thing. If you have enough torque to spin up heavier tires/wheels and enough brake to slow them down, go for it. But remember that the rubber needs to stay properly planted on the the road surface in order to work effectively.

Heavier tire/rims also increase unsprung weight. A big increase in unsprung weight can have an pretty nasty impact on your car's handling if the course is bumpy.

In a perfect world, more/stickier rubber would always mean faster times but it doesn't work that way. It's all about finding the right compromise.

yeah really Great info Thanks

[Fair!]

An 8" wheel would obviously be better but there's nothing wrong with putting a 225 50 15 on a 7". And I would go with the 225 for sure. 710's last way longer than Hoosiers so I'd also go with those.

+1 to all of this.



We ran 225/50/15 Hankook Z212 (9.2" of section width!) on a 15x7" wheel on our E30 and it cleared with room everywhere, no fender rolling. We were limited to a 7.5" wide wheel for this class (STS) but ony found affordable/light 15x7 options as the time. It "worked" and still made skidpad numbers that humilitated many R compound competitors...