I'm installing OB struts on my '90 Legacy and will put on larger diameter tires, but is there a reason to go to a 15'' rim?

A 205/75R14 is very close in width and height to a 205/70R15.

Thanks

I would *think* you would go with the size of rims that would match the type of tire you wish to run.

For example: I am kind of partial to LT tires, specifically 85 series 10 ply tires, that seem to be availaible to me for the best price/size in tires that require a 16" rim. So my "choice" is 16" rims, because I'm buying rims anyway, but if I already owned rims that I could fit a tire I wanted then I would choose something different in a tire.

I'm installing OB struts on my '90 Legacy and will put on larger diameter tires, but is there a reason to go to a 15'' rim?

A 205/75R14 is very close in width and height to a 205/70R15.

Thanks

 

14's of the same outside diameter and width are cheaper, give a better ride and actually better grip both forward and sidways, due to the increased sidewall giving the tread a better spread on the ground.

 

And 14's are 'way cheaper.

 

I cannot think of a reason to go to 15's, except possibly a few ounces of weight. Under very hard use they may be more stable, with less sidewall to deflect.

 

At least that's what I've heard and believe. :-p

14's of the same outside diameter and width are cheaper, give a better ride and actually better grip both forward and sidways, due to the increased sidewall giving the tread a better spread on the ground.

 

Are you talking about offroad or something? Shorter sidewalls will be stiffer and do a better job at keeping the tread in contact with the road, providing better grip and increased responsiveness.

The bigger your tires, the deeper the snow. But, I cant really see the need to go from 14s to 15s. Def. a smoother ride with the 14s.

What about you can fit a bigger brake calipers/pads in the 15:banana:

 

 

 

The bigger your tires, the deeper the snow. But, I cant really see the need to go from 14s to 15s. Def. a smoother ride with the 14s.

What about you can fit a bigger brake calipers/pads in the 15:banana:

 

Touche.

I've been shopping for struts for my '90 Legacy wagon, is there a reason to go with the OB struts over the OEM struts?

If you want a 4-inch lift, then yes.

Hmm, got me thinking now. I was originally going to put 16" low profile wheels/tires on the car and lower it about an inch, but the extra 4" of clearance for next winter sure would be nice. Perhaps I'll do the lowpro for the summer and install the OB struts next fall when I put my winter tires on.

Originally Posted by uniberp

14's of the same outside diameter and width are cheaper, give a better ride and actually better grip both forward and sidways, due to the increased sidewall giving the tread a better spread on the ground.

 

Are you talking about offroad or something? Shorter sidewalls will be stiffer and do a better job at keeping the tread in contact with the road, providing better grip and increased responsiveness.

 

 

Nope. IMO (and IME), for street use, low profile tires will not grip as well as 14's of the same outside diameter, compound and tread. Several factors are involved.

1. the larger tread patch due to greater flexibility.

2. The increased sidewall deformity allows more tire to stay on the ground under forward acceleration. (see dragster tires)

3. The softer sidewall allows the tire to conform more easily to road surface irregularities.

 

It's sort of the same logic that's applied to make certain racing tires seem as soft as silly putty.

 

Granted, stiffer sidewalls give you a more precise road feel, which for some

may translate into greater confidence at speed, but don't mistake feeling for numbers.

 

I have seen and recorded numbers on several cars that confirm this, at least for me.

Nope. IMO (and IME), for street use, low profile tires will not grip as well as 14's of the same outside diameter, compound and tread. Several factors are involved.

1. the larger tread patch due to greater flexibility. Yes, there is a bit more deflection and a very very small increase in contact patch, but it's pretty much insignificant.

The tread is the same width, you're running the same pressure. The only added contact you'll be getting is from the sidewall as it rolls over under cornering. Riding on the sidewall does not increase grip. To maximize grip you want the actual tread surface to stay flat on the road, which means stiffer, shorter sidewalls. I won't even get into the camber curve issues because we're just talking about tires.

2. The increased sidewall deformity allows more tire to stay on the ground under forward acceleration. (see dragster tires)

These are not drag slicks. To get the kind of deformation that increases grip under acceleration you need to be running like 10psi. You really can't compare the two.

 

It's sort of the same logic that's applied to make certain racing tires seem as soft as silly putty.

yes racing tires do have soft compounds, so that they stick to the ground. The sidewalls, however, are extremely stiff, in order to keep that sticky surface on the ground and to decrease slip angles. Watch an F1 car with a flat tire or blowout. They can drive around on just the sidewalls.

 

Granted, stiffer sidewalls give you a more precise road feel, which for some

may translate into greater confidence at speed, but don't mistake feeling for numbers.

 

I have seen and recorded numbers on several cars that confirm this, at least for me.

 

I'd like to see these numbers.

 

Not to mention the fact that "more precise road feel" and increased responsiveness do to the lower slip angles needed to generate cornering forces mean a whole lot when it comes to good handling. Even if an 85 series tire could generate just as much cornering force on a skid pad as a 40-series, it would be a lot slower on a slalom or a road course or something.

The tread is the same width, you're running the same pressure. The only added contact you'll be getting is from the sidewall as it rolls over under cornering. Riding on the sidewall does not increase grip. To maximize grip you want the actual tread surface to stay flat on the road, which means stiffer, shorter sidewalls. I won't even get into the camber curve issues because we're just talking about tires.

These are not drag slicks. To get the kind of deformation that increases grip under acceleration you need to be running like 10psi. You really can't compare the two.

 

 

yes racing tires do have soft compounds, so that they stick to the ground. The sidewalls, however, are extremely stiff, in order to keep that sticky surface on the ground and to decrease slip angles. Watch an F1 car with a flat tire or blowout. They can drive around on just the sidewalls.

 

 

 

I'd like to see these numbers.

 

Not to mention the fact that "more precise road feel" and increased responsiveness do to the lower slip angles needed to generate cornering forces mean a whole lot when it comes to good handling. Even if an 85 series tire could generate just as much cornering force on a skid pad as a 40-series, it would be a lot slower on a slalom or a road course or something.

Yes, $2000 worth of tires and wheels will make a big difference, but not as much as suspension upgrades. For regular use, there is no significant difference between 14 and 15 except price.

I'm not talking about $2000 in wheels and tires. You said a taller tire grips better. It doesn't.

I'm not talking about $2000 in wheels and tires. You said a taller tire grips better. It doesn't.

 

I am of a different opinion.