My instructor at a track event was checkin out my car, and saw that I was running 205/50/16 yoko a520's on the rear and 225/45/16 fk451's in the front. He said mixed tire sizes is a BIG no no... someone care to explain why?
I wouldn't call it a big no-no, just another way to induce a bit more oversteer. Some instructors usually tend to prefer people from 'installing' more oversteer in their cars since it's generally a more advanced driving technique. I don't know what else it could be...
Different tire sizes aren't a problem in my eyes, it's just another way to tune a car. Different tire models/brands is generally a no-no, that might be what he was referring to.
You end up with different grip levels and different reactions to temperature change. This generally is going to make tuning difficult. I'm not saying people can't do it, but this is more advanced than staggered tire sizes and would require more testing/tuning to get right.
I ran Hoosier A's in 245/45/16 up front, and 225/50/16 in the rear. Not because I ordered them that way, but because I got them really cheap from a local S2000 autoXer. I probably used 4 sets in that configuration, and I had no problems with the tires or grip.
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Chris @ DeatschWerks (Fuel Nerd)
1991 CRX SiR
1991 Civic Wagon RT4WD
ah... that makes alot more sense now. For some reason, I've always heard of ppl using different tire sizes for autox, but I noticed at the last track event Billy, David, JP, and Drew were all using same size/brand all around. Thnx for the replies
One of the main reason for using the same tire size all around is the ability to rotate the tires.
DR would rotate his tires after every race session. Front to back. Back to front.
With two different sizes, this is obviously a bad idea. A staggered setup would turn quickly to understeer.
Now if you don't rotate your tires very often then you may find some benefit like some more oversteer out of a staggered setup. I'd just recommend a bigger swaybar though.
The reason I had different tires wasn't because I was trying to tune the car to respond in any particular way haha. I was just cheap and stuck with the 2 tires that came with the set of 4 rims I bought. JP actually read the sidewall and found out they were made in 2000....
One of the main reason for using the same tire size all around is the ability to rotate the tires.
DR would rotate his tires after every race session. Front to back. Back to front.
With two different sizes, this is obviously a bad idea. A staggered setup would turn quickly to understeer.
Being able to rotate is nice, but not that big of a deal to me. The way I see it I don't waste my "good" wide rubber holding the rear of my car up, I use some less expensive tire, and the rears last longer than the fronts.
Being able to rotate is nice, but not that big of a deal to me. The way I see it I don't waste my "good" wide rubber holding the rear of my car up, I use some less expensive tire, and the rears last longer than the fronts.
Yeah but on a track car, where 99% of the cornering is steady-state, wouldnt you want the maximum amount of tire all the way around? If the back end has less grip than the front, wont your steady-state speed be limited by the least common denominator? I understand the need for it in highly transitional situations like autox, but I would think it would be detrimental to take tire off the car for a track car. Unless the rear could maintain the same g-load as the front with less tire.
DR would rotate his tires after every race session. Front to back. Back to front.
I'm beginning to think paul might be a stalker...
But, back to the topic, I see no issue in running different sizes front to back. I acctually thought about running 205's in the rear for auto-x. As for differnt tires all together, I probably wouldn't do that, but, as in Danny's case, o well. For the recreational HPDE guy I don't see it as that big of a deal.
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1999 Premium White Pearl Type SH
Well...I could fit the 245/45/16 up front, but it wouldn't fit in the rear (too wide). There isn't much of a difference in contact patch from the 245 to the 225, but every little bit helps, eh? Especially with how heavy our cars are. Also, the 245 (24.4") is a little smaller diameter tire vs. the 225 (24.8"), and I have stock gearing.
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Chris @ DeatschWerks (Fuel Nerd)
1991 CRX SiR
1991 Civic Wagon RT4WD
A sligh change in tire size will not cause the ATTS unit to disable. If is set to disable when the spare is on. Not sure exactly what it has but it can tell that all 4 corners are not level. And anyone thats driving hard enough to use ATTS with the spare on is just stupid...
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1999 Premium White Pearl Type SH
Wouldn't different tire radii confuse ABS, too? Different makes of tires of the same size can still have different radii, or distances traveld per revolution, although the differences are generally small.
Wouldn't different tire radii confuse ABS, too? Different makes of tires of the same size can still have different radii, or distances traveld per revolution, although the differences are generally small.
that is true but the difference is so small i don't think it would make a difference.
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1999 Premium White Pearl Type SH
I thought about trying a 245/50/15 on the front with a 225/50/15 on the rear. I still have a pair of 245/50/15s, so I should try that to see how well it fits.
Yeah but on a track car, where 99% of the cornering is steady-state, wouldnt you want the maximum amount of tire all the way around? If the back end has less grip than the front, wont your steady-state speed be limited by the least common denominator? I understand the need for it in highly transitional situations like autox, but I would think it would be detrimental to take tire off the car for a track car. Unless the rear could maintain the same g-load as the front with less tire.
Totally agree.
I want the stickiest tire with the widest contact patch I can buy for my budget. Rotation can easily be achieved in other ways...tire pressure, sway bars, spring/shock dampning, weight transfer/throttle modulation.
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