Tire Size Advice

[glen242]

I want to stay with 27" tires on my stock 15" wheels. I am thinking on mixing sizes, 255-60 on the rear, and 225-70 on the front.

Anyone doing this? How is the handling compared to stock tire sizes?

Any WAG on how this would work, if you are not running this combination?

Thanks,

 

[The73vetteman]

Hi Glen,
Let me give you my 2 cents. My car had 275 60s on the rear and 225 70s on the front when I bought it. Earlier this year I went with BFG Radial TAs, 225 70 all round. Frankly I'm happier with the new rubber. It rides nicer and is using a little less gas. I can't say how the on-the-limit handling compares because we don't have many curves here in Michigan.

Now how much of this is down to tire width and how much to BFG vs Goodyear I can't say. Overall though, my feeling is that unless you're putting down a lot of hp and torque, go with the stock.

John

 

[pgtr]

I want to stay with 27" tires on my stock 15" wheels. I am thinking on mixing sizes, 255-60 on the rear, and 225-70 on the front.

Anyone doing this? How is the handling compared to stock tire sizes?

Any WAG on how this would work, if you are not running this combination?

Thanks,

Tire size is not necessarily the ticket to improved performance given your constraints. Since you are interested in staggering your tires I'm presuming you are interested in handling performance? Staggering can be an excellent way to improve handling particularly if the car is prone to oversteer. But it should be done in conjunction with staggered rims. Are you experiencing oversteer?

Frankly it's not going to help much with stock 15" tires. In fact the 255/60s may yield even greater sidewall flex on an 8" rim...?

Bottom line is that there are NO performance tires available in 15" 60 series tires for a C3. Last I checked they are all highway radials w/ relatively hard rubber and flexy sidewalls.

The performance tires I'm aware of for 15X8 rims are limited to 225/70R15s - consider a full set of V or H speed rated tires such as Goodyear Eagle RS-A, Firestone PV41, General XP-2000 V4, Michelin Pilot XGT H4. These are true performance tires and will substantially outperform ANY 255/60 tire.

 

[wishuwerehere82]

When I got my 82 it had 275/60's on the back and 245/60's on the front. It had a tendency to get loose in the rear and sort of rock forward on rises in the road.
Sort of like having a real big spring bouncing in the back.
Almost catapulted my head into the T_tops a couple of times.:L
I have 255/60-15's all around low and love the feel of the car compared to the old set. It rides more level on the road and has a lot better handling on curves now. Now the whole car rises and falls as the road rises without any forward rocking. It doesn't have the hotwheels look, but it's way more comfortable.

 

[glen242]

Keep the info coming. I'm still on the fence, but sort of leaning towards stock size, 225-70, front and rear.

I got the car about 7 years ago with U rated 215-65 tires. Did my first 2000 RPM clutch dump since the new 383 went in and smoked them like a bad cigar. That is the reason I was considering 255-60 for the rear. Almost 1" more tread width.

All comments appreciated.

Thanks,

 

[pgtr]

Are you interested in straight line hole shot performance, drive-in peel outs or lateral (sports car like) handling performance at low and high speeds? My input is only limited to the later I'm afraid.

Keep in mind ALL 255/60s are hard rubber compound non-performacne tires with relatively soft sidewalls. The majority of 225/70s are the same but there are a 'few' softer rubber tires (mentioned above) that are stronger and offer superior performance - they are a bit more expensive than the cheaper cosmetic performance tires. The V or H rated 225s will outperform any S/T rated 255/60s in any objective performance measurement I'm aware of regardless of the 1" difference in width. Performance is more dependent upon the rubber compound properties and internal construction like add'l belts. However specifically in off the line performance a soft squishy sidewall may actually be desirable...?

Personally I will only use at a bare minimum H-speed rated, A-temperature rated tires with a mid-level treadwear (~300s) rating on ANY of our personal vehicles.

 

[Evolution1980]

If you go 225 all around, you can get a bit more life out of your tires because you can rotate them front-rear-left-right. If you get different sizes front-back, you are limited to just a right-left rotation.

My $.02 is the most meat in the rear (255's) and responsive tracking up front with 235's. I'm actually running 245's up front only because I like the beefier look over the 235's. 255 is the largest I can run in back.

As pgtr stated, it's goign to be difficult to find real performance tires that will work well with the car if you still have the 15" rims.
They are all going to be lower profile, narrower tires. This will really give you a bone-jarring ride as well as looking kinda funny without lowering the car significantly. Also, you can't get white letter radials ("WLR") in high performance tires.

If you are running the stock rim with 275's....first, I'm surprised anyone could/would mount that big on the stock rim. Second, the sidewall is certainly going to give you a lot more flex, which will translate into a sloppy/squishy feel in the rear especially in corners.

 

[glen242]

pgtr

Sports car handling.

Any opinion on Sumitomo HTR 200? Good reviews on Tire Rack, speed rated 'H' and the price is right.

I only put on +/- 1000 miles per year. The tires age before the tread is gone, so I don't want to get into real high buck tires that I will have to throw away in 10 years.

Those 1000 miles are, for the most part, 'spirited' driving, hence the 383.

Gotta remember I'm an old man! Don't hang out at drive-ins , etc. like 40 years ago!

Thanks,

 

[The73vetteman]

If you are running the stock rim with 275's....first, I'm surprised anyone could/would mount that big on the stock rim. Second, the sidewall is certainly going to give you a lot more flex, which will translate into a sloppy/squishy feel in the rear especially in corners.[/quote]

Absolutely. The sidewalls really ballooned out which gave the car an unattractive look, and the cornering did have a squishy oversteering feel (although that may also have been due to the worn out bushings.)

Like I said, if you're running the stock wheel size I'd go with the the stock rubber (or close to - I can understand that 255s might look better.)

If it's improved handling or a more modern appearance you're after what you want is a lower aspect ratio. One way to go about this is to fit a bigger wheel so you can keep the wheel diameter, and hence the gearing, unchanged.

I've probably gone way off topic here but it's an area I find interesting. Apologies for rambling on ......

J

 

[glen242]

If you are running the stock rim with 275's....first, I'm surprised anyone could/would mount that big on the stock rim. Second, the sidewall is certainly going to give you a lot more flex, which will translate into a sloppy/squishy feel in the rear especially in corners.

Absolutely. The sidewalls really ballooned out which gave the car an unattractive look, and the cornering did have a squishy oversteering feel (although that may also have been due to the worn out bushings.)

Like I said, if you're running the stock wheel size I'd go with the the stock rubber (or close to - I can understand that 255s might look better.)

If it's improved handling or a more modern appearance you're after what you want is a lower aspect ratio. One way to go about this is to fit a bigger wheel so you can keep the wheel diameter, and hence the gearing, unchanged.

I've probably gone way off topic here but it's an area I find interesting. Apologies for rambling on ......

J[/quote]

Don't have 275s was not considering 275s. I believe you misread my post.

 

[Evolution1980]

Don't have 275s was not considering 275s. I believe you misread my post.

I think he quoted me and I was referencing wishyouwerehere82's post...

 

[pgtr]

pgtr

Sports car handling.

Any opinion on Sumitomo HTR 200? Good reviews on Tire Rack, speed rated 'H' and the price is right.

I only put on +/- 1000 miles per year. The tires age before the tread is gone, so I don't want to get into real high buck tires that I will have to throw away in 10 years.

Those 1000 miles are, for the most part, 'spirited' driving, hence the 383.

Gotta remember I'm an old man! Don't hang out at drive-ins , etc. like 40 years ago!

Thanks,

My initial reaction before clicking over was so so. I had a set of Sumis some years back (nonCorvette) and only had so so impressions (originally purchased because of their then connection to Dunlops).

But I clicked over out of curiosity and must say that is an incredible price for H rated SUMMER tires! That's a fraction of what a good set of PV41s would run. Note that they are summer tires meaning they will be slicker 'n snot in sub 30 deg temps even in the dry.

All I can say is on paper that looks like a steal - essentially the same price as the cosmetic (non) performance tires that are the usual fare for these cars. Heck I'm tempted to buy a set and toss them in the attic (and out of the sun) at that price myself - thanks for the tip.

The Michelin Pilots and Cooper GTHs are H rated and while less than the police tires like the PV41s and XP2000s are certainly more expensive than the closeouts you found. The Coopers have long since been dropped and I'm wondering if the same has happened to the pilots (tirerack isn't carrying them anymore).

While sitting here I'm suddenly realizing my memory is in error - there are (or were?) 2 hi perf tires still avail in 255/60 15s. The Pirelli Scorpion Zero and Kumho Ecsta STX. No idea if either is still available.

Not to alarm you but I am mostly speaking in past tense in many cases above. Since most tire buyers for 15" rims on a vintage Corvette seem to prefer cheap cosmetic performance tires I've watched the selection of performance tires trickle from a modest handfull to just a few left. I suspect those tires you found being on closeout may signifying they too are being discontinued. My prediction is that we are fast arriving at just the 2 police tires (expensive but very good) for 15" within the next year or two. And even their days could be numbered since most police cars sport 16" and 17" rims.

Thanks for the heads up!

 

[glen242]

....
While sitting here I'm suddenly realizing my memory is in error - there are (or were?) 2 hi perf tires still avail in 255/60 15s. The Pirelli Scorpion Zero and Kumho Ecsta STX. No idea if either is still available.

Not to alarm you but I am mostly speaking in past tense in many cases above. Since most tire buyers for 15" rims on a vintage Corvette seem to prefer cheap cosmetic performance tires I've watched the selection of performance tires trickle from a modest handfull to just a few left. I suspect those tires you found being on closeout may signifying they too are being discontinued. My prediction is that we are fast arriving at just the 2 police tires (expensive but very good) for 15" within the next year or two. And even their days could be numbered since most police cars sport 16" and 17" rims.

Thanks for the heads up!

Pirelli and Kumho are no longer available.

As for the discontinued HR 200, here is what Sumitomo had to say "The HTR 200 line has long been available with container loads only ! " No mention on their web site of being discontinued. I don't know what the container load means, but a guess would be, a distributor or what ever, would have to buy a container load? Maybe the Tire Rack bought a container load, is getting low on that tire, and decided not to buy another container load. Just a guess.

Tires have been shipped.

Thanks,