Scaff
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Often a forgotten area of tuning, the correct tyre choice can make a huge difference to all areas of the car, its effect on braking having already been covered in detail in the GT4 & Brakes thread.
With this in mind, along with the regularly asked question which tyres are most like real ones, I set about putting together a number of tests that could then be compared to real world test data. What you choose to do with the following information (a helpful basis for tuning or just setting up the car as close to real both spring to mind) you should always keep in mind that the results I have provided only apply to one car (BMW M3) and are purely indicative, as a margin for error certainly exists within these tests.
I will not be taking about the characteristics of each tyre type, as this is a very, very subjective area. By dealing with the data below I hope it will allow for a slightly more subjective look at this subject.
Even given the above, I hope that you find the results as interesting as I found the testing.
The Tests
Lateral G
Using a scale map of the Grand Valley speedway and a lot of patience I have mapped out approximate radiuses for three of the main corners on the circuit. These three are the two main hairpins and the sweeper after the bridge.
The approximate radius for each of these corners is:
1st Hairpin 193 ft
2nd Hairpin 110 ft
Sweeper 359 ft
Once the radius of each corner was found it was possible to calculate the cornering speed for a 1g car and then calculate the lateral g of a GT4 BMW M3 with a range of tyres fitted.
The formula I have used is taken from Skip Barbers book Speed Matter and is a slightly simplified version of the one found in the Physics of Racing series.
The formula is
15 * G * R = MPH2
G = lateral G and R = Corner Radius in feet
MPH2 = Cornering speed in MPH, squared.
For example a 1g car in a 100 foot radius corner, would have a maximum cornering speed of :
15 * 1 * 100 = 1,500
1,500 = 38.73 mph
This calculation actually gives an accurate indication of a cars maximum cornering speed for a corner of a given radius.
When looking at the results below you should always keep in mind that while the calculation above is very valid, the corner radius figures are approximate calculations and the speeds taken from the data logger as a high average cornering speed. Additionally while lateral g figures are a very useful indicator of both a cars cornering ability and the tyres level of grip, they are not easily transferable. Just because an M3 corners at Xg around a certain corner does not mean another car can on the same tyre type. As I mentioned above, they results will be indicative, not absolute.
For comparison I have found actual test telemetry data for a BMW M3, now while the radius of the corners is not shown in this data, taken over two laps the results are linked below.
http://europeancarweb.com/tech/0509ec_suspension_04_z.jpg
http://europeancarweb.com/tech/0509ec_suspension_05_z.jpg
The main corners of interest here are 2, 3 and 4; which indicate that a stock BMW M3 has a peak Lateral g of 1.15 and can maintain an average g as high as 0.96. Its these two figures I will mainly be looking at for comparison.
Acceleration and Deceleration
The second set of tests will be looking at the standard test data from the UK magazine Autocar, it covers a range of acceleration and decelerations tests, some through the gears and others in a set gear.
The Autocar test in question was carried out on 14.02.01, which can be found on the Autocar website.
In addition I also used the 0-100-0 test figures from the 2003 Autocar 0-100-0 tests, links to this can be found on the first page of the GT4 & Brakes thread.
These tests will be carried out with the tyres from the first test that most closely match real world figures for lateral g.
Results Lateral G
The table below shows the details of the Lateral G results for each tyre type tested, along with the corresponding speed (in MPH), lap time and average speed.
The tyre type that most closely matches that of the real world test data are the N2 tyres, with a Lateral g range of 0.99 & 1.1.
N1 tyres grip level was well below that of the real test data, and while the N3 tyres were close, they remain a little on the high side. One thing that is of interest, that some may not be aware of, is how much of a difference in overall laptime a small increase in cornering speed gives. Over the three corners measured, the N3 tyres increased cornering speed by 1.5mph, 0.7mph and 0.3mph respectively, but in total the reduction in laptime was 3.172 seconds.
The S2 tyres take the level of grip in the realm of track-only tyres, while the R spec tyres increased the cornering forces and speeds to very high levels. This is particularly clear to see in the R5 tyres, which recorded a high of 1.68g, which for a stock M3 is amazing. To put into context, on the final sweeper the cornering speed difference between N2 and R5 tyres is an astonishing 19mph.
The two tyres I took forward to the second set of tests are the N2 and N3 tyres, so lets have a look at what happened here.
Results - Acceleration and Deceleration
The two sets of tests are both taken from the UK magazine Autocar, and consist of the figures from the original roadtest (dated 14/2/01) and the 2003 0-100-0mph test.
The two sets of data were obtained from a number of separate runs, and conducted with all driver aids switched off. The two tyre types used were the N2 and N3 spec, and the results compared with the actual Autocar figures. Obviously some margin has to be allowed with regard to the results, to account for the differences in real world conditions and GT4 conditions.
Starting with the through the gears roadtest results, the N2 tyres posted times slower that the Autocar figures, with the N3 tyres posting closer times. The difference between the N3 and Autocar figures could be improved on by cleaner launches (no driver aids remember), as the 30-70mph through the gears figures are very close.
The 60-0mph brake test figures are almost exact matches with both the N2 and N3 tyres, while the top speed test is a bit misleading as a standard M3 is limited to 155mph (although BMW speed limiters are always a bit generous) GT4 does not limit any cars top speed.
The set of figures that differ the most are the in-gear acceleration results, in each and every case the GT4 M3 is slower. Now its interesting to note that in-gear acceleration of this type is not something you would normally do on track. It really is a representation of a drivetrains flexibility when driving on-road in the real world.
When racing and in GT4 you would not accelerate from 50 to 70 mph using only fifth or sixth gear. As a result it is unlikely to effect driving in GT4, but it does appear to be an area that was not considered to be important in GT4. It is also important to remember that at present I only have data for the M3 with regard to this; further testing will be required to see if this is a common issue.
The 0-100-0 mph tests were carried out separately from the roadtest results. The two tyre types both performed well in the run through the gears to 100mph, with the times at each increment being close to the Autocar results, again with the N3 tyres being the closest to 100mph, better launches may improve on these.
The 100-0 times for both tyres easily beat the real world times, and this backs up my finding from past 0-100-0 tests I have carried out (see the GT4 & Brakes thread). The N3s creeping slightly ahead here.
If the reaction time is removed from the times, it can be seen that overall the N2 tyres are very close to the final Autocar time, with the N3 tyres ahead slightly.
conclusion
Given the above I would say that the N2 tyres seem to be the closest match for real world M3 figures, for the majority of the tests, and better launches on my part may improve on this. The N3 tyres on balance have just slightly too much grip in the lateral G tests and while close on the Roadtest, I feel that the difference it makes in average speed and laptime is just too great.
However, as I said at the start these results are not conclusive, but merely and indicator of the differences in the tyre types. It is a useful start and something that I hope to have the time to look at for with other cars (and other games).
Regards
Scaff
With this in mind, along with the regularly asked question which tyres are most like real ones, I set about putting together a number of tests that could then be compared to real world test data. What you choose to do with the following information (a helpful basis for tuning or just setting up the car as close to real both spring to mind) you should always keep in mind that the results I have provided only apply to one car (BMW M3) and are purely indicative, as a margin for error certainly exists within these tests.
I will not be taking about the characteristics of each tyre type, as this is a very, very subjective area. By dealing with the data below I hope it will allow for a slightly more subjective look at this subject.
Even given the above, I hope that you find the results as interesting as I found the testing.
The Tests
Lateral G
Using a scale map of the Grand Valley speedway and a lot of patience I have mapped out approximate radiuses for three of the main corners on the circuit. These three are the two main hairpins and the sweeper after the bridge.
The approximate radius for each of these corners is:
1st Hairpin 193 ft
2nd Hairpin 110 ft
Sweeper 359 ft
Once the radius of each corner was found it was possible to calculate the cornering speed for a 1g car and then calculate the lateral g of a GT4 BMW M3 with a range of tyres fitted.
The formula I have used is taken from Skip Barbers book Speed Matter and is a slightly simplified version of the one found in the Physics of Racing series.
The formula is
15 * G * R = MPH2
G = lateral G and R = Corner Radius in feet
MPH2 = Cornering speed in MPH, squared.
For example a 1g car in a 100 foot radius corner, would have a maximum cornering speed of :
15 * 1 * 100 = 1,500
1,500 = 38.73 mph
This calculation actually gives an accurate indication of a cars maximum cornering speed for a corner of a given radius.
When looking at the results below you should always keep in mind that while the calculation above is very valid, the corner radius figures are approximate calculations and the speeds taken from the data logger as a high average cornering speed. Additionally while lateral g figures are a very useful indicator of both a cars cornering ability and the tyres level of grip, they are not easily transferable. Just because an M3 corners at Xg around a certain corner does not mean another car can on the same tyre type. As I mentioned above, they results will be indicative, not absolute.
For comparison I have found actual test telemetry data for a BMW M3, now while the radius of the corners is not shown in this data, taken over two laps the results are linked below.
http://europeancarweb.com/tech/0509ec_suspension_04_z.jpg
http://europeancarweb.com/tech/0509ec_suspension_05_z.jpg
The main corners of interest here are 2, 3 and 4; which indicate that a stock BMW M3 has a peak Lateral g of 1.15 and can maintain an average g as high as 0.96. Its these two figures I will mainly be looking at for comparison.
Acceleration and Deceleration
The second set of tests will be looking at the standard test data from the UK magazine Autocar, it covers a range of acceleration and decelerations tests, some through the gears and others in a set gear.
The Autocar test in question was carried out on 14.02.01, which can be found on the Autocar website.
In addition I also used the 0-100-0 test figures from the 2003 Autocar 0-100-0 tests, links to this can be found on the first page of the GT4 & Brakes thread.
These tests will be carried out with the tyres from the first test that most closely match real world figures for lateral g.
Results Lateral G
The table below shows the details of the Lateral G results for each tyre type tested, along with the corresponding speed (in MPH), lap time and average speed.
The tyre type that most closely matches that of the real world test data are the N2 tyres, with a Lateral g range of 0.99 & 1.1.
N1 tyres grip level was well below that of the real test data, and while the N3 tyres were close, they remain a little on the high side. One thing that is of interest, that some may not be aware of, is how much of a difference in overall laptime a small increase in cornering speed gives. Over the three corners measured, the N3 tyres increased cornering speed by 1.5mph, 0.7mph and 0.3mph respectively, but in total the reduction in laptime was 3.172 seconds.
The S2 tyres take the level of grip in the realm of track-only tyres, while the R spec tyres increased the cornering forces and speeds to very high levels. This is particularly clear to see in the R5 tyres, which recorded a high of 1.68g, which for a stock M3 is amazing. To put into context, on the final sweeper the cornering speed difference between N2 and R5 tyres is an astonishing 19mph.
The two tyres I took forward to the second set of tests are the N2 and N3 tyres, so lets have a look at what happened here.
Results - Acceleration and Deceleration
The two sets of tests are both taken from the UK magazine Autocar, and consist of the figures from the original roadtest (dated 14/2/01) and the 2003 0-100-0mph test.
The two sets of data were obtained from a number of separate runs, and conducted with all driver aids switched off. The two tyre types used were the N2 and N3 spec, and the results compared with the actual Autocar figures. Obviously some margin has to be allowed with regard to the results, to account for the differences in real world conditions and GT4 conditions.
Starting with the through the gears roadtest results, the N2 tyres posted times slower that the Autocar figures, with the N3 tyres posting closer times. The difference between the N3 and Autocar figures could be improved on by cleaner launches (no driver aids remember), as the 30-70mph through the gears figures are very close.
The 60-0mph brake test figures are almost exact matches with both the N2 and N3 tyres, while the top speed test is a bit misleading as a standard M3 is limited to 155mph (although BMW speed limiters are always a bit generous) GT4 does not limit any cars top speed.
The set of figures that differ the most are the in-gear acceleration results, in each and every case the GT4 M3 is slower. Now its interesting to note that in-gear acceleration of this type is not something you would normally do on track. It really is a representation of a drivetrains flexibility when driving on-road in the real world.
When racing and in GT4 you would not accelerate from 50 to 70 mph using only fifth or sixth gear. As a result it is unlikely to effect driving in GT4, but it does appear to be an area that was not considered to be important in GT4. It is also important to remember that at present I only have data for the M3 with regard to this; further testing will be required to see if this is a common issue.
The 0-100-0 mph tests were carried out separately from the roadtest results. The two tyre types both performed well in the run through the gears to 100mph, with the times at each increment being close to the Autocar results, again with the N3 tyres being the closest to 100mph, better launches may improve on these.
The 100-0 times for both tyres easily beat the real world times, and this backs up my finding from past 0-100-0 tests I have carried out (see the GT4 & Brakes thread). The N3s creeping slightly ahead here.
If the reaction time is removed from the times, it can be seen that overall the N2 tyres are very close to the final Autocar time, with the N3 tyres ahead slightly.
conclusion
Given the above I would say that the N2 tyres seem to be the closest match for real world M3 figures, for the majority of the tests, and better launches on my part may improve on this. The N3 tyres on balance have just slightly too much grip in the lateral G tests and while close on the Roadtest, I feel that the difference it makes in average speed and laptime is just too great.
However, as I said at the start these results are not conclusive, but merely and indicator of the differences in the tyre types. It is a useful start and something that I hope to have the time to look at for with other cars (and other games).
Regards
Scaff
and awd wheelspin is not very fun thing on sixth gear when going over 160 mph.. 
👍
